1 /*
2 * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/bufferingOopClosure.hpp"
32 #include "gc/g1/concurrentMarkThread.inline.hpp"
33 #include "gc/g1/g1Allocator.inline.hpp"
34 #include "gc/g1/g1CollectedHeap.inline.hpp"
35 #include "gc/g1/g1CollectionSet.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ConcurrentRefine.hpp"
39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1FullCollector.hpp"
42 #include "gc/g1/g1FullGCScope.hpp"
43 #include "gc/g1/g1GCPhaseTimes.hpp"
44 #include "gc/g1/g1GCServicabilitySupport.hpp"
45 #include "gc/g1/g1HeapSizingPolicy.hpp"
46 #include "gc/g1/g1HeapTransition.hpp"
47 #include "gc/g1/g1HeapVerifier.hpp"
48 #include "gc/g1/g1HotCardCache.hpp"
49 #include "gc/g1/g1OopClosures.inline.hpp"
50 #include "gc/g1/g1ParScanThreadState.inline.hpp"
51 #include "gc/g1/g1Policy.hpp"
52 #include "gc/g1/g1RegionToSpaceMapper.hpp"
53 #include "gc/g1/g1RemSet.hpp"
54 #include "gc/g1/g1RootClosures.hpp"
55 #include "gc/g1/g1RootProcessor.hpp"
56 #include "gc/g1/g1StringDedup.hpp"
57 #include "gc/g1/g1YCTypes.hpp"
58 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
59 #include "gc/g1/heapRegion.inline.hpp"
60 #include "gc/g1/heapRegionRemSet.hpp"
61 #include "gc/g1/heapRegionSet.inline.hpp"
62 #include "gc/g1/vm_operations_g1.hpp"
63 #include "gc/shared/gcHeapSummary.hpp"
64 #include "gc/shared/gcId.hpp"
65 #include "gc/shared/gcLocker.inline.hpp"
66 #include "gc/shared/gcTimer.hpp"
67 #include "gc/shared/gcTrace.hpp"
68 #include "gc/shared/gcTraceTime.inline.hpp"
69 #include "gc/shared/generationSpec.hpp"
70 #include "gc/shared/isGCActiveMark.hpp"
71 #include "gc/shared/preservedMarks.inline.hpp"
72 #include "gc/shared/suspendibleThreadSet.hpp"
73 #include "gc/shared/referenceProcessor.inline.hpp"
74 #include "gc/shared/taskqueue.inline.hpp"
75 #include "gc/shared/weakProcessor.hpp"
76 #include "logging/log.hpp"
77 #include "memory/allocation.hpp"
78 #include "memory/iterator.hpp"
79 #include "memory/resourceArea.hpp"
80 #include "oops/oop.inline.hpp"
81 #include "prims/resolvedMethodTable.hpp"
82 #include "runtime/atomic.hpp"
83 #include "runtime/init.hpp"
84 #include "runtime/orderAccess.inline.hpp"
85 #include "runtime/vmThread.hpp"
86 #include "utilities/align.hpp"
87 #include "utilities/globalDefinitions.hpp"
88 #include "utilities/stack.inline.hpp"
89
90 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
91
92 // INVARIANTS/NOTES
93 //
94 // All allocation activity covered by the G1CollectedHeap interface is
95 // serialized by acquiring the HeapLock. This happens in mem_allocate
96 // and allocate_new_tlab, which are the "entry" points to the
97 // allocation code from the rest of the JVM. (Note that this does not
98 // apply to TLAB allocation, which is not part of this interface: it
99 // is done by clients of this interface.)
100
101 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
102 private:
103 size_t _num_dirtied;
104 G1CollectedHeap* _g1h;
105 G1SATBCardTableLoggingModRefBS* _g1_bs;
106
107 HeapRegion* region_for_card(jbyte* card_ptr) const {
108 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
109 }
110
111 bool will_become_free(HeapRegion* hr) const {
112 // A region will be freed by free_collection_set if the region is in the
113 // collection set and has not had an evacuation failure.
114 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
115 }
116
117 public:
118 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
119 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
120
121 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
122 HeapRegion* hr = region_for_card(card_ptr);
123
124 // Should only dirty cards in regions that won't be freed.
125 if (!will_become_free(hr)) {
126 *card_ptr = CardTableModRefBS::dirty_card_val();
127 _num_dirtied++;
128 }
129
130 return true;
131 }
132
133 size_t num_dirtied() const { return _num_dirtied; }
134 };
135
136
137 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
138 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
139 }
140
141 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
142 // The from card cache is not the memory that is actually committed. So we cannot
143 // take advantage of the zero_filled parameter.
144 reset_from_card_cache(start_idx, num_regions);
145 }
146
147
148 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
149 MemRegion mr) {
150 return new HeapRegion(hrs_index, bot(), mr);
151 }
152
153 // Private methods.
154
155 HeapRegion*
156 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
157 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
158 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
159 if (!_secondary_free_list.is_empty()) {
160 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
161 "secondary_free_list has %u entries",
162 _secondary_free_list.length());
163 // It looks as if there are free regions available on the
164 // secondary_free_list. Let's move them to the free_list and try
165 // again to allocate from it.
166 append_secondary_free_list();
167
168 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
169 "empty we should have moved at least one entry to the free_list");
170 HeapRegion* res = _hrm.allocate_free_region(is_old);
171 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
172 "allocated " HR_FORMAT " from secondary_free_list",
173 HR_FORMAT_PARAMS(res));
174 return res;
175 }
176
177 // Wait here until we get notified either when (a) there are no
178 // more free regions coming or (b) some regions have been moved on
179 // the secondary_free_list.
180 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
181 }
182
183 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
184 "could not allocate from secondary_free_list");
185 return NULL;
186 }
187
188 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
189 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
190 "the only time we use this to allocate a humongous region is "
191 "when we are allocating a single humongous region");
192
193 HeapRegion* res;
194 if (G1StressConcRegionFreeing) {
195 if (!_secondary_free_list.is_empty()) {
196 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
197 "forced to look at the secondary_free_list");
198 res = new_region_try_secondary_free_list(is_old);
199 if (res != NULL) {
200 return res;
201 }
202 }
203 }
204
205 res = _hrm.allocate_free_region(is_old);
206
207 if (res == NULL) {
208 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
209 "res == NULL, trying the secondary_free_list");
210 res = new_region_try_secondary_free_list(is_old);
211 }
212 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
213 // Currently, only attempts to allocate GC alloc regions set
214 // do_expand to true. So, we should only reach here during a
215 // safepoint. If this assumption changes we might have to
216 // reconsider the use of _expand_heap_after_alloc_failure.
217 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
218
219 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
220 word_size * HeapWordSize);
221
222 if (expand(word_size * HeapWordSize)) {
223 // Given that expand() succeeded in expanding the heap, and we
224 // always expand the heap by an amount aligned to the heap
225 // region size, the free list should in theory not be empty.
226 // In either case allocate_free_region() will check for NULL.
227 res = _hrm.allocate_free_region(is_old);
228 } else {
229 _expand_heap_after_alloc_failure = false;
230 }
231 }
232 return res;
233 }
234
235 HeapWord*
236 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
237 uint num_regions,
238 size_t word_size,
239 AllocationContext_t context) {
240 assert(first != G1_NO_HRM_INDEX, "pre-condition");
241 assert(is_humongous(word_size), "word_size should be humongous");
242 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
243
244 // Index of last region in the series.
245 uint last = first + num_regions - 1;
246
247 // We need to initialize the region(s) we just discovered. This is
248 // a bit tricky given that it can happen concurrently with
249 // refinement threads refining cards on these regions and
250 // potentially wanting to refine the BOT as they are scanning
251 // those cards (this can happen shortly after a cleanup; see CR
252 // 6991377). So we have to set up the region(s) carefully and in
253 // a specific order.
254
255 // The word size sum of all the regions we will allocate.
256 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
257 assert(word_size <= word_size_sum, "sanity");
258
259 // This will be the "starts humongous" region.
260 HeapRegion* first_hr = region_at(first);
261 // The header of the new object will be placed at the bottom of
262 // the first region.
263 HeapWord* new_obj = first_hr->bottom();
264 // This will be the new top of the new object.
265 HeapWord* obj_top = new_obj + word_size;
266
267 // First, we need to zero the header of the space that we will be
268 // allocating. When we update top further down, some refinement
269 // threads might try to scan the region. By zeroing the header we
270 // ensure that any thread that will try to scan the region will
271 // come across the zero klass word and bail out.
272 //
273 // NOTE: It would not have been correct to have used
274 // CollectedHeap::fill_with_object() and make the space look like
275 // an int array. The thread that is doing the allocation will
276 // later update the object header to a potentially different array
277 // type and, for a very short period of time, the klass and length
278 // fields will be inconsistent. This could cause a refinement
279 // thread to calculate the object size incorrectly.
280 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
281
282 // Next, pad out the unused tail of the last region with filler
283 // objects, for improved usage accounting.
284 // How many words we use for filler objects.
285 size_t word_fill_size = word_size_sum - word_size;
286
287 // How many words memory we "waste" which cannot hold a filler object.
288 size_t words_not_fillable = 0;
289
290 if (word_fill_size >= min_fill_size()) {
291 fill_with_objects(obj_top, word_fill_size);
292 } else if (word_fill_size > 0) {
293 // We have space to fill, but we cannot fit an object there.
294 words_not_fillable = word_fill_size;
295 word_fill_size = 0;
296 }
297
298 // We will set up the first region as "starts humongous". This
299 // will also update the BOT covering all the regions to reflect
300 // that there is a single object that starts at the bottom of the
301 // first region.
302 first_hr->set_starts_humongous(obj_top, word_fill_size);
303 first_hr->set_allocation_context(context);
304 // Then, if there are any, we will set up the "continues
305 // humongous" regions.
306 HeapRegion* hr = NULL;
307 for (uint i = first + 1; i <= last; ++i) {
308 hr = region_at(i);
309 hr->set_continues_humongous(first_hr);
310 hr->set_allocation_context(context);
311 }
312
313 // Up to this point no concurrent thread would have been able to
314 // do any scanning on any region in this series. All the top
315 // fields still point to bottom, so the intersection between
316 // [bottom,top] and [card_start,card_end] will be empty. Before we
317 // update the top fields, we'll do a storestore to make sure that
318 // no thread sees the update to top before the zeroing of the
319 // object header and the BOT initialization.
320 OrderAccess::storestore();
321
322 // Now, we will update the top fields of the "continues humongous"
323 // regions except the last one.
324 for (uint i = first; i < last; ++i) {
325 hr = region_at(i);
326 hr->set_top(hr->end());
327 }
328
329 hr = region_at(last);
330 // If we cannot fit a filler object, we must set top to the end
331 // of the humongous object, otherwise we cannot iterate the heap
332 // and the BOT will not be complete.
333 hr->set_top(hr->end() - words_not_fillable);
334
335 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
336 "obj_top should be in last region");
337
338 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
339
340 assert(words_not_fillable == 0 ||
341 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
342 "Miscalculation in humongous allocation");
343
344 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
345
346 for (uint i = first; i <= last; ++i) {
347 hr = region_at(i);
348 _humongous_set.add(hr);
349 _hr_printer.alloc(hr);
350 }
351
352 return new_obj;
353 }
354
355 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
356 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
357 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
358 }
359
360 // If could fit into free regions w/o expansion, try.
361 // Otherwise, if can expand, do so.
362 // Otherwise, if using ex regions might help, try with ex given back.
363 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
364 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
365
366 _verifier->verify_region_sets_optional();
367
368 uint first = G1_NO_HRM_INDEX;
369 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
370
371 if (obj_regions == 1) {
372 // Only one region to allocate, try to use a fast path by directly allocating
373 // from the free lists. Do not try to expand here, we will potentially do that
374 // later.
375 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
376 if (hr != NULL) {
377 first = hr->hrm_index();
378 }
379 } else {
380 // We can't allocate humongous regions spanning more than one region while
381 // cleanupComplete() is running, since some of the regions we find to be
382 // empty might not yet be added to the free list. It is not straightforward
383 // to know in which list they are on so that we can remove them. We only
384 // need to do this if we need to allocate more than one region to satisfy the
385 // current humongous allocation request. If we are only allocating one region
386 // we use the one-region region allocation code (see above), that already
387 // potentially waits for regions from the secondary free list.
388 wait_while_free_regions_coming();
389 append_secondary_free_list_if_not_empty_with_lock();
390
391 // Policy: Try only empty regions (i.e. already committed first). Maybe we
392 // are lucky enough to find some.
393 first = _hrm.find_contiguous_only_empty(obj_regions);
394 if (first != G1_NO_HRM_INDEX) {
395 _hrm.allocate_free_regions_starting_at(first, obj_regions);
396 }
397 }
398
399 if (first == G1_NO_HRM_INDEX) {
400 // Policy: We could not find enough regions for the humongous object in the
401 // free list. Look through the heap to find a mix of free and uncommitted regions.
402 // If so, try expansion.
403 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
404 if (first != G1_NO_HRM_INDEX) {
405 // We found something. Make sure these regions are committed, i.e. expand
406 // the heap. Alternatively we could do a defragmentation GC.
407 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
408 word_size * HeapWordSize);
409
410 _hrm.expand_at(first, obj_regions, workers());
411 g1_policy()->record_new_heap_size(num_regions());
412
413 #ifdef ASSERT
414 for (uint i = first; i < first + obj_regions; ++i) {
415 HeapRegion* hr = region_at(i);
416 assert(hr->is_free(), "sanity");
417 assert(hr->is_empty(), "sanity");
418 assert(is_on_master_free_list(hr), "sanity");
419 }
420 #endif
421 _hrm.allocate_free_regions_starting_at(first, obj_regions);
422 } else {
423 // Policy: Potentially trigger a defragmentation GC.
424 }
425 }
426
427 HeapWord* result = NULL;
428 if (first != G1_NO_HRM_INDEX) {
429 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
430 word_size, context);
431 assert(result != NULL, "it should always return a valid result");
432
433 // A successful humongous object allocation changes the used space
434 // information of the old generation so we need to recalculate the
435 // sizes and update the jstat counters here.
436 g1mm()->update_sizes();
437 }
438
439 _verifier->verify_region_sets_optional();
440
441 return result;
442 }
443
444 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
445 assert_heap_not_locked_and_not_at_safepoint();
446 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
447
448 uint dummy_gc_count_before;
449 uint dummy_gclocker_retry_count = 0;
450 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
451 }
452
453 HeapWord*
454 G1CollectedHeap::mem_allocate(size_t word_size,
455 bool* gc_overhead_limit_was_exceeded) {
456 assert_heap_not_locked_and_not_at_safepoint();
457
458 // Loop until the allocation is satisfied, or unsatisfied after GC.
459 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
460 uint gc_count_before;
461
462 HeapWord* result = NULL;
463 if (!is_humongous(word_size)) {
464 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
465 } else {
466 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
467 }
468 if (result != NULL) {
469 return result;
470 }
471
472 // Create the garbage collection operation...
473 VM_G1CollectForAllocation op(gc_count_before, word_size);
474 op.set_allocation_context(AllocationContext::current());
475
476 // ...and get the VM thread to execute it.
477 VMThread::execute(&op);
478
479 if (op.prologue_succeeded() && op.pause_succeeded()) {
480 // If the operation was successful we'll return the result even
481 // if it is NULL. If the allocation attempt failed immediately
482 // after a Full GC, it's unlikely we'll be able to allocate now.
483 HeapWord* result = op.result();
484 if (result != NULL && !is_humongous(word_size)) {
485 // Allocations that take place on VM operations do not do any
486 // card dirtying and we have to do it here. We only have to do
487 // this for non-humongous allocations, though.
488 dirty_young_block(result, word_size);
489 }
490 return result;
491 } else {
492 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
493 return NULL;
494 }
495 assert(op.result() == NULL,
496 "the result should be NULL if the VM op did not succeed");
497 }
498
499 // Give a warning if we seem to be looping forever.
500 if ((QueuedAllocationWarningCount > 0) &&
501 (try_count % QueuedAllocationWarningCount == 0)) {
502 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
503 }
504 }
505
506 ShouldNotReachHere();
507 return NULL;
508 }
509
510 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
511 AllocationContext_t context,
512 uint* gc_count_before_ret,
513 uint* gclocker_retry_count_ret) {
514 // Make sure you read the note in attempt_allocation_humongous().
515
516 assert_heap_not_locked_and_not_at_safepoint();
517 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
518 "be called for humongous allocation requests");
519
520 // We should only get here after the first-level allocation attempt
521 // (attempt_allocation()) failed to allocate.
522
523 // We will loop until a) we manage to successfully perform the
524 // allocation or b) we successfully schedule a collection which
525 // fails to perform the allocation. b) is the only case when we'll
526 // return NULL.
527 HeapWord* result = NULL;
528 for (int try_count = 1; /* we'll return */; try_count += 1) {
529 bool should_try_gc;
530 uint gc_count_before;
531
532 {
533 MutexLockerEx x(Heap_lock);
534 result = _allocator->attempt_allocation_locked(word_size, context);
535 if (result != NULL) {
536 return result;
537 }
538
539 if (GCLocker::is_active_and_needs_gc()) {
540 if (g1_policy()->can_expand_young_list()) {
541 // No need for an ergo verbose message here,
542 // can_expand_young_list() does this when it returns true.
543 result = _allocator->attempt_allocation_force(word_size, context);
544 if (result != NULL) {
545 return result;
546 }
547 }
548 should_try_gc = false;
549 } else {
550 // The GCLocker may not be active but the GCLocker initiated
551 // GC may not yet have been performed (GCLocker::needs_gc()
552 // returns true). In this case we do not try this GC and
553 // wait until the GCLocker initiated GC is performed, and
554 // then retry the allocation.
555 if (GCLocker::needs_gc()) {
556 should_try_gc = false;
557 } else {
558 // Read the GC count while still holding the Heap_lock.
559 gc_count_before = total_collections();
560 should_try_gc = true;
561 }
562 }
563 }
564
565 if (should_try_gc) {
566 bool succeeded;
567 result = do_collection_pause(word_size, gc_count_before, &succeeded,
568 GCCause::_g1_inc_collection_pause);
569 if (result != NULL) {
570 assert(succeeded, "only way to get back a non-NULL result");
571 return result;
572 }
573
574 if (succeeded) {
575 // If we get here we successfully scheduled a collection which
576 // failed to allocate. No point in trying to allocate
577 // further. We'll just return NULL.
578 MutexLockerEx x(Heap_lock);
579 *gc_count_before_ret = total_collections();
580 return NULL;
581 }
582 } else {
583 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
584 MutexLockerEx x(Heap_lock);
585 *gc_count_before_ret = total_collections();
586 return NULL;
587 }
588 // The GCLocker is either active or the GCLocker initiated
589 // GC has not yet been performed. Stall until it is and
590 // then retry the allocation.
591 GCLocker::stall_until_clear();
592 (*gclocker_retry_count_ret) += 1;
593 }
594
595 // We can reach here if we were unsuccessful in scheduling a
596 // collection (because another thread beat us to it) or if we were
597 // stalled due to the GC locker. In either can we should retry the
598 // allocation attempt in case another thread successfully
599 // performed a collection and reclaimed enough space. We do the
600 // first attempt (without holding the Heap_lock) here and the
601 // follow-on attempt will be at the start of the next loop
602 // iteration (after taking the Heap_lock).
603 result = _allocator->attempt_allocation(word_size, context);
604 if (result != NULL) {
605 return result;
606 }
607
608 // Give a warning if we seem to be looping forever.
609 if ((QueuedAllocationWarningCount > 0) &&
610 (try_count % QueuedAllocationWarningCount == 0)) {
611 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
612 "retries %d times", try_count);
613 }
614 }
615
616 ShouldNotReachHere();
617 return NULL;
618 }
619
620 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
621 assert_at_safepoint(true /* should_be_vm_thread */);
622 if (_archive_allocator == NULL) {
623 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
624 }
625 }
626
627 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
628 // Allocations in archive regions cannot be of a size that would be considered
629 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
630 // may be different at archive-restore time.
631 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
632 }
633
634 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
635 assert_at_safepoint(true /* should_be_vm_thread */);
636 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
637 if (is_archive_alloc_too_large(word_size)) {
638 return NULL;
639 }
640 return _archive_allocator->archive_mem_allocate(word_size);
641 }
642
643 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
644 size_t end_alignment_in_bytes) {
645 assert_at_safepoint(true /* should_be_vm_thread */);
646 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
647
648 // Call complete_archive to do the real work, filling in the MemRegion
649 // array with the archive regions.
650 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
651 delete _archive_allocator;
652 _archive_allocator = NULL;
653 }
654
655 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
656 assert(ranges != NULL, "MemRegion array NULL");
657 assert(count != 0, "No MemRegions provided");
658 MemRegion reserved = _hrm.reserved();
659 for (size_t i = 0; i < count; i++) {
660 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
661 return false;
662 }
663 }
664 return true;
665 }
666
667 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
668 size_t count,
669 bool open) {
670 assert(!is_init_completed(), "Expect to be called at JVM init time");
671 assert(ranges != NULL, "MemRegion array NULL");
672 assert(count != 0, "No MemRegions provided");
673 MutexLockerEx x(Heap_lock);
674
675 MemRegion reserved = _hrm.reserved();
676 HeapWord* prev_last_addr = NULL;
677 HeapRegion* prev_last_region = NULL;
678
679 // Temporarily disable pretouching of heap pages. This interface is used
680 // when mmap'ing archived heap data in, so pre-touching is wasted.
681 FlagSetting fs(AlwaysPreTouch, false);
682
683 // Enable archive object checking used by G1MarkSweep. We have to let it know
684 // about each archive range, so that objects in those ranges aren't marked.
685 G1ArchiveAllocator::enable_archive_object_check();
686
687 // For each specified MemRegion range, allocate the corresponding G1
688 // regions and mark them as archive regions. We expect the ranges
689 // in ascending starting address order, without overlap.
690 for (size_t i = 0; i < count; i++) {
691 MemRegion curr_range = ranges[i];
692 HeapWord* start_address = curr_range.start();
693 size_t word_size = curr_range.word_size();
694 HeapWord* last_address = curr_range.last();
695 size_t commits = 0;
696
697 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
698 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
699 p2i(start_address), p2i(last_address));
700 guarantee(start_address > prev_last_addr,
701 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
702 p2i(start_address), p2i(prev_last_addr));
703 prev_last_addr = last_address;
704
705 // Check for ranges that start in the same G1 region in which the previous
706 // range ended, and adjust the start address so we don't try to allocate
707 // the same region again. If the current range is entirely within that
708 // region, skip it, just adjusting the recorded top.
709 HeapRegion* start_region = _hrm.addr_to_region(start_address);
710 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
711 start_address = start_region->end();
712 if (start_address > last_address) {
713 increase_used(word_size * HeapWordSize);
714 start_region->set_top(last_address + 1);
715 continue;
716 }
717 start_region->set_top(start_address);
718 curr_range = MemRegion(start_address, last_address + 1);
719 start_region = _hrm.addr_to_region(start_address);
720 }
721
722 // Perform the actual region allocation, exiting if it fails.
723 // Then note how much new space we have allocated.
724 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
725 return false;
726 }
727 increase_used(word_size * HeapWordSize);
728 if (commits != 0) {
729 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
730 HeapRegion::GrainWords * HeapWordSize * commits);
731
732 }
733
734 // Mark each G1 region touched by the range as archive, add it to
735 // the old set, and set the allocation context and top.
736 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
737 HeapRegion* last_region = _hrm.addr_to_region(last_address);
738 prev_last_region = last_region;
739
740 while (curr_region != NULL) {
741 assert(curr_region->is_empty() && !curr_region->is_pinned(),
742 "Region already in use (index %u)", curr_region->hrm_index());
743 curr_region->set_allocation_context(AllocationContext::system());
744 if (open) {
745 curr_region->set_open_archive();
746 } else {
747 curr_region->set_closed_archive();
748 }
749 _hr_printer.alloc(curr_region);
750 _old_set.add(curr_region);
751 HeapWord* top;
752 HeapRegion* next_region;
753 if (curr_region != last_region) {
754 top = curr_region->end();
755 next_region = _hrm.next_region_in_heap(curr_region);
756 } else {
757 top = last_address + 1;
758 next_region = NULL;
759 }
760 curr_region->set_top(top);
761 curr_region->set_first_dead(top);
762 curr_region->set_end_of_live(top);
763 curr_region = next_region;
764 }
765
766 // Notify mark-sweep of the archive
767 G1ArchiveAllocator::set_range_archive(curr_range, open);
768 }
769 return true;
770 }
771
772 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
773 assert(!is_init_completed(), "Expect to be called at JVM init time");
774 assert(ranges != NULL, "MemRegion array NULL");
775 assert(count != 0, "No MemRegions provided");
776 MemRegion reserved = _hrm.reserved();
777 HeapWord *prev_last_addr = NULL;
778 HeapRegion* prev_last_region = NULL;
779
780 // For each MemRegion, create filler objects, if needed, in the G1 regions
781 // that contain the address range. The address range actually within the
782 // MemRegion will not be modified. That is assumed to have been initialized
783 // elsewhere, probably via an mmap of archived heap data.
784 MutexLockerEx x(Heap_lock);
785 for (size_t i = 0; i < count; i++) {
786 HeapWord* start_address = ranges[i].start();
787 HeapWord* last_address = ranges[i].last();
788
789 assert(reserved.contains(start_address) && reserved.contains(last_address),
790 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
791 p2i(start_address), p2i(last_address));
792 assert(start_address > prev_last_addr,
793 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
794 p2i(start_address), p2i(prev_last_addr));
795
796 HeapRegion* start_region = _hrm.addr_to_region(start_address);
797 HeapRegion* last_region = _hrm.addr_to_region(last_address);
798 HeapWord* bottom_address = start_region->bottom();
799
800 // Check for a range beginning in the same region in which the
801 // previous one ended.
802 if (start_region == prev_last_region) {
803 bottom_address = prev_last_addr + 1;
804 }
805
806 // Verify that the regions were all marked as archive regions by
807 // alloc_archive_regions.
808 HeapRegion* curr_region = start_region;
809 while (curr_region != NULL) {
810 guarantee(curr_region->is_archive(),
811 "Expected archive region at index %u", curr_region->hrm_index());
812 if (curr_region != last_region) {
813 curr_region = _hrm.next_region_in_heap(curr_region);
814 } else {
815 curr_region = NULL;
816 }
817 }
818
819 prev_last_addr = last_address;
820 prev_last_region = last_region;
821
822 // Fill the memory below the allocated range with dummy object(s),
823 // if the region bottom does not match the range start, or if the previous
824 // range ended within the same G1 region, and there is a gap.
825 if (start_address != bottom_address) {
826 size_t fill_size = pointer_delta(start_address, bottom_address);
827 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
828 increase_used(fill_size * HeapWordSize);
829 }
830 }
831 }
832
833 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
834 uint* gc_count_before_ret,
835 uint* gclocker_retry_count_ret) {
836 assert_heap_not_locked_and_not_at_safepoint();
837 assert(!is_humongous(word_size), "attempt_allocation() should not "
838 "be called for humongous allocation requests");
839
840 AllocationContext_t context = AllocationContext::current();
841 HeapWord* result = _allocator->attempt_allocation(word_size, context);
842
843 if (result == NULL) {
844 result = attempt_allocation_slow(word_size,
845 context,
846 gc_count_before_ret,
847 gclocker_retry_count_ret);
848 }
849 assert_heap_not_locked();
850 if (result != NULL) {
851 dirty_young_block(result, word_size);
852 }
853 return result;
854 }
855
856 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
857 assert(!is_init_completed(), "Expect to be called at JVM init time");
858 assert(ranges != NULL, "MemRegion array NULL");
859 assert(count != 0, "No MemRegions provided");
860 MemRegion reserved = _hrm.reserved();
861 HeapWord* prev_last_addr = NULL;
862 HeapRegion* prev_last_region = NULL;
863 size_t size_used = 0;
864 size_t uncommitted_regions = 0;
865
866 // For each Memregion, free the G1 regions that constitute it, and
867 // notify mark-sweep that the range is no longer to be considered 'archive.'
868 MutexLockerEx x(Heap_lock);
869 for (size_t i = 0; i < count; i++) {
870 HeapWord* start_address = ranges[i].start();
871 HeapWord* last_address = ranges[i].last();
872
873 assert(reserved.contains(start_address) && reserved.contains(last_address),
874 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
875 p2i(start_address), p2i(last_address));
876 assert(start_address > prev_last_addr,
877 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
878 p2i(start_address), p2i(prev_last_addr));
879 size_used += ranges[i].byte_size();
880 prev_last_addr = last_address;
881
882 HeapRegion* start_region = _hrm.addr_to_region(start_address);
883 HeapRegion* last_region = _hrm.addr_to_region(last_address);
884
885 // Check for ranges that start in the same G1 region in which the previous
886 // range ended, and adjust the start address so we don't try to free
887 // the same region again. If the current range is entirely within that
888 // region, skip it.
889 if (start_region == prev_last_region) {
890 start_address = start_region->end();
891 if (start_address > last_address) {
892 continue;
893 }
894 start_region = _hrm.addr_to_region(start_address);
895 }
896 prev_last_region = last_region;
897
898 // After verifying that each region was marked as an archive region by
899 // alloc_archive_regions, set it free and empty and uncommit it.
900 HeapRegion* curr_region = start_region;
901 while (curr_region != NULL) {
902 guarantee(curr_region->is_archive(),
903 "Expected archive region at index %u", curr_region->hrm_index());
904 uint curr_index = curr_region->hrm_index();
905 _old_set.remove(curr_region);
906 curr_region->set_free();
907 curr_region->set_top(curr_region->bottom());
908 if (curr_region != last_region) {
909 curr_region = _hrm.next_region_in_heap(curr_region);
910 } else {
911 curr_region = NULL;
912 }
913 _hrm.shrink_at(curr_index, 1);
914 uncommitted_regions++;
915 }
916
917 // Notify mark-sweep that this is no longer an archive range.
918 G1ArchiveAllocator::set_range_archive(ranges[i], false);
919 }
920
921 if (uncommitted_regions != 0) {
922 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
923 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
924 }
925 decrease_used(size_used);
926 }
927
928 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
929 uint* gc_count_before_ret,
930 uint* gclocker_retry_count_ret) {
931 // The structure of this method has a lot of similarities to
932 // attempt_allocation_slow(). The reason these two were not merged
933 // into a single one is that such a method would require several "if
934 // allocation is not humongous do this, otherwise do that"
935 // conditional paths which would obscure its flow. In fact, an early
936 // version of this code did use a unified method which was harder to
937 // follow and, as a result, it had subtle bugs that were hard to
938 // track down. So keeping these two methods separate allows each to
939 // be more readable. It will be good to keep these two in sync as
940 // much as possible.
941
942 assert_heap_not_locked_and_not_at_safepoint();
943 assert(is_humongous(word_size), "attempt_allocation_humongous() "
944 "should only be called for humongous allocations");
945
946 // Humongous objects can exhaust the heap quickly, so we should check if we
947 // need to start a marking cycle at each humongous object allocation. We do
948 // the check before we do the actual allocation. The reason for doing it
949 // before the allocation is that we avoid having to keep track of the newly
950 // allocated memory while we do a GC.
951 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
952 word_size)) {
953 collect(GCCause::_g1_humongous_allocation);
954 }
955
956 // We will loop until a) we manage to successfully perform the
957 // allocation or b) we successfully schedule a collection which
958 // fails to perform the allocation. b) is the only case when we'll
959 // return NULL.
960 HeapWord* result = NULL;
961 for (int try_count = 1; /* we'll return */; try_count += 1) {
962 bool should_try_gc;
963 uint gc_count_before;
964
965 {
966 MutexLockerEx x(Heap_lock);
967
968 // Given that humongous objects are not allocated in young
969 // regions, we'll first try to do the allocation without doing a
970 // collection hoping that there's enough space in the heap.
971 result = humongous_obj_allocate(word_size, AllocationContext::current());
972 if (result != NULL) {
973 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
974 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
975 return result;
976 }
977
978 if (GCLocker::is_active_and_needs_gc()) {
979 should_try_gc = false;
980 } else {
981 // The GCLocker may not be active but the GCLocker initiated
982 // GC may not yet have been performed (GCLocker::needs_gc()
983 // returns true). In this case we do not try this GC and
984 // wait until the GCLocker initiated GC is performed, and
985 // then retry the allocation.
986 if (GCLocker::needs_gc()) {
987 should_try_gc = false;
988 } else {
989 // Read the GC count while still holding the Heap_lock.
990 gc_count_before = total_collections();
991 should_try_gc = true;
992 }
993 }
994 }
995
996 if (should_try_gc) {
997 // If we failed to allocate the humongous object, we should try to
998 // do a collection pause (if we're allowed) in case it reclaims
999 // enough space for the allocation to succeed after the pause.
1000
1001 bool succeeded;
1002 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1003 GCCause::_g1_humongous_allocation);
1004 if (result != NULL) {
1005 assert(succeeded, "only way to get back a non-NULL result");
1006 return result;
1007 }
1008
1009 if (succeeded) {
1010 // If we get here we successfully scheduled a collection which
1011 // failed to allocate. No point in trying to allocate
1012 // further. We'll just return NULL.
1013 MutexLockerEx x(Heap_lock);
1014 *gc_count_before_ret = total_collections();
1015 return NULL;
1016 }
1017 } else {
1018 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1019 MutexLockerEx x(Heap_lock);
1020 *gc_count_before_ret = total_collections();
1021 return NULL;
1022 }
1023 // The GCLocker is either active or the GCLocker initiated
1024 // GC has not yet been performed. Stall until it is and
1025 // then retry the allocation.
1026 GCLocker::stall_until_clear();
1027 (*gclocker_retry_count_ret) += 1;
1028 }
1029
1030 // We can reach here if we were unsuccessful in scheduling a
1031 // collection (because another thread beat us to it) or if we were
1032 // stalled due to the GC locker. In either can we should retry the
1033 // allocation attempt in case another thread successfully
1034 // performed a collection and reclaimed enough space. Give a
1035 // warning if we seem to be looping forever.
1036
1037 if ((QueuedAllocationWarningCount > 0) &&
1038 (try_count % QueuedAllocationWarningCount == 0)) {
1039 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1040 "retries %d times", try_count);
1041 }
1042 }
1043
1044 ShouldNotReachHere();
1045 return NULL;
1046 }
1047
1048 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1049 AllocationContext_t context,
1050 bool expect_null_mutator_alloc_region) {
1051 assert_at_safepoint(true /* should_be_vm_thread */);
1052 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1053 "the current alloc region was unexpectedly found to be non-NULL");
1054
1055 if (!is_humongous(word_size)) {
1056 return _allocator->attempt_allocation_locked(word_size, context);
1057 } else {
1058 HeapWord* result = humongous_obj_allocate(word_size, context);
1059 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1060 collector_state()->set_initiate_conc_mark_if_possible(true);
1061 }
1062 return result;
1063 }
1064
1065 ShouldNotReachHere();
1066 }
1067
1068 class PostCompactionPrinterClosure: public HeapRegionClosure {
1069 private:
1070 G1HRPrinter* _hr_printer;
1071 public:
1072 bool doHeapRegion(HeapRegion* hr) {
1073 assert(!hr->is_young(), "not expecting to find young regions");
1074 _hr_printer->post_compaction(hr);
1075 return false;
1076 }
1077
1078 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1079 : _hr_printer(hr_printer) { }
1080 };
1081
1082 void G1CollectedHeap::print_hrm_post_compaction() {
1083 if (_hr_printer.is_active()) {
1084 PostCompactionPrinterClosure cl(hr_printer());
1085 heap_region_iterate(&cl);
1086 }
1087
1088 }
1089
1090 void G1CollectedHeap::abort_concurrent_cycle() {
1091 // Note: When we have a more flexible GC logging framework that
1092 // allows us to add optional attributes to a GC log record we
1093 // could consider timing and reporting how long we wait in the
1094 // following two methods.
1095 wait_while_free_regions_coming();
1096 // If we start the compaction before the CM threads finish
1097 // scanning the root regions we might trip them over as we'll
1098 // be moving objects / updating references. So let's wait until
1099 // they are done. By telling them to abort, they should complete
1100 // early.
1101 _cm->root_regions()->abort();
1102 _cm->root_regions()->wait_until_scan_finished();
1103 append_secondary_free_list_if_not_empty_with_lock();
1104
1105 // Disable discovery and empty the discovered lists
1106 // for the CM ref processor.
1107 ref_processor_cm()->disable_discovery();
1108 ref_processor_cm()->abandon_partial_discovery();
1109 ref_processor_cm()->verify_no_references_recorded();
1110
1111 // Abandon current iterations of concurrent marking and concurrent
1112 // refinement, if any are in progress.
1113 concurrent_mark()->abort();
1114 }
1115
1116 void G1CollectedHeap::prepare_heap_for_full_collection() {
1117 // Make sure we'll choose a new allocation region afterwards.
1118 _allocator->release_mutator_alloc_region();
1119 _allocator->abandon_gc_alloc_regions();
1120 g1_rem_set()->cleanupHRRS();
1121
1122 // We may have added regions to the current incremental collection
1123 // set between the last GC or pause and now. We need to clear the
1124 // incremental collection set and then start rebuilding it afresh
1125 // after this full GC.
1126 abandon_collection_set(collection_set());
1127
1128 tear_down_region_sets(false /* free_list_only */);
1129 collector_state()->set_gcs_are_young(true);
1130 }
1131
1132 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1133 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1134 assert(used() == recalculate_used(), "Should be equal");
1135 _verifier->verify_region_sets_optional();
1136 _verifier->verify_before_gc();
1137 _verifier->check_bitmaps("Full GC Start");
1138 }
1139
1140 void G1CollectedHeap::prepare_heap_for_mutators() {
1141 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1142 ClassLoaderDataGraph::purge();
1143 MetaspaceAux::verify_metrics();
1144
1145 // Prepare heap for normal collections.
1146 assert(num_free_regions() == 0, "we should not have added any free regions");
1147 rebuild_region_sets(false /* free_list_only */);
1148 abort_refinement();
1149 resize_if_necessary_after_full_collection();
1150
1151 // Rebuild the strong code root lists for each region
1152 rebuild_strong_code_roots();
1153
1154 // Start a new incremental collection set for the next pause
1155 start_new_collection_set();
1156
1157 _allocator->init_mutator_alloc_region();
1158
1159 // Post collection state updates.
1160 MetaspaceGC::compute_new_size();
1161 }
1162
1163 void G1CollectedHeap::abort_refinement() {
1164 if (_hot_card_cache->use_cache()) {
1165 _hot_card_cache->reset_hot_cache();
1166 }
1167
1168 // Discard all remembered set updates.
1169 JavaThread::dirty_card_queue_set().abandon_logs();
1170 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1171 }
1172
1173 void G1CollectedHeap::verify_after_full_collection() {
1174 check_gc_time_stamps();
1175 _hrm.verify_optional();
1176 _verifier->verify_region_sets_optional();
1177 _verifier->verify_after_gc();
1178 // Clear the previous marking bitmap, if needed for bitmap verification.
1179 // Note we cannot do this when we clear the next marking bitmap in
1180 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1181 // objects marked during a full GC against the previous bitmap.
1182 // But we need to clear it before calling check_bitmaps below since
1183 // the full GC has compacted objects and updated TAMS but not updated
1184 // the prev bitmap.
1185 if (G1VerifyBitmaps) {
1186 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1187 _cm->clear_prev_bitmap(workers());
1188 }
1189 _verifier->check_bitmaps("Full GC End");
1190
1191 // At this point there should be no regions in the
1192 // entire heap tagged as young.
1193 assert(check_young_list_empty(), "young list should be empty at this point");
1194
1195 // Note: since we've just done a full GC, concurrent
1196 // marking is no longer active. Therefore we need not
1197 // re-enable reference discovery for the CM ref processor.
1198 // That will be done at the start of the next marking cycle.
1199 // We also know that the STW processor should no longer
1200 // discover any new references.
1201 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1202 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1203 ref_processor_stw()->verify_no_references_recorded();
1204 ref_processor_cm()->verify_no_references_recorded();
1205 }
1206
1207 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1208 // Post collection logging.
1209 // We should do this after we potentially resize the heap so
1210 // that all the COMMIT / UNCOMMIT events are generated before
1211 // the compaction events.
1212 print_hrm_post_compaction();
1213 heap_transition->print();
1214 print_heap_after_gc();
1215 print_heap_regions();
1216 #ifdef TRACESPINNING
1217 ParallelTaskTerminator::print_termination_counts();
1218 #endif
1219 }
1220
1221 void G1CollectedHeap::do_full_collection_inner(G1FullGCScope* scope) {
1222 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1223 g1_policy()->record_full_collection_start();
1224
1225 print_heap_before_gc();
1226 print_heap_regions();
1227
1228 abort_concurrent_cycle();
1229 verify_before_full_collection(scope->is_explicit_gc());
1230
1231 gc_prologue(true);
1232 prepare_heap_for_full_collection();
1233
1234 G1FullCollector collector(scope, ref_processor_stw(), concurrent_mark()->next_mark_bitmap(), workers()->active_workers());
1235 collector.prepare_collection();
1236 collector.collect();
1237 collector.complete_collection();
1238
1239 prepare_heap_for_mutators();
1240
1241 g1_policy()->record_full_collection_end();
1242 gc_epilogue(true);
1243
1244 verify_after_full_collection();
1245
1246 print_heap_after_full_collection(scope->heap_transition());
1247 }
1248
1249 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1250 bool clear_all_soft_refs) {
1251 assert_at_safepoint(true /* should_be_vm_thread */);
1252
1253 if (GCLocker::check_active_before_gc()) {
1254 // Full GC was not completed.
1255 return false;
1256 }
1257
1258 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1259 collector_policy()->should_clear_all_soft_refs();
1260
1261 G1FullGCScope scope(explicit_gc, do_clear_all_soft_refs);
1262 do_full_collection_inner(&scope);
1263
1264 // Full collection was successfully completed.
1265 return true;
1266 }
1267
1268 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1269 // Currently, there is no facility in the do_full_collection(bool) API to notify
1270 // the caller that the collection did not succeed (e.g., because it was locked
1271 // out by the GC locker). So, right now, we'll ignore the return value.
1272 bool dummy = do_full_collection(true, /* explicit_gc */
1273 clear_all_soft_refs);
1274 }
1275
1276 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1277 // Capacity, free and used after the GC counted as full regions to
1278 // include the waste in the following calculations.
1279 const size_t capacity_after_gc = capacity();
1280 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1281
1282 // This is enforced in arguments.cpp.
1283 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1284 "otherwise the code below doesn't make sense");
1285
1286 // We don't have floating point command-line arguments
1287 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1288 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1289 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1290 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1291
1292 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1293 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1294
1295 // We have to be careful here as these two calculations can overflow
1296 // 32-bit size_t's.
1297 double used_after_gc_d = (double) used_after_gc;
1298 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1299 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1300
1301 // Let's make sure that they are both under the max heap size, which
1302 // by default will make them fit into a size_t.
1303 double desired_capacity_upper_bound = (double) max_heap_size;
1304 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1305 desired_capacity_upper_bound);
1306 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1307 desired_capacity_upper_bound);
1308
1309 // We can now safely turn them into size_t's.
1310 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1311 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1312
1313 // This assert only makes sense here, before we adjust them
1314 // with respect to the min and max heap size.
1315 assert(minimum_desired_capacity <= maximum_desired_capacity,
1316 "minimum_desired_capacity = " SIZE_FORMAT ", "
1317 "maximum_desired_capacity = " SIZE_FORMAT,
1318 minimum_desired_capacity, maximum_desired_capacity);
1319
1320 // Should not be greater than the heap max size. No need to adjust
1321 // it with respect to the heap min size as it's a lower bound (i.e.,
1322 // we'll try to make the capacity larger than it, not smaller).
1323 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1324 // Should not be less than the heap min size. No need to adjust it
1325 // with respect to the heap max size as it's an upper bound (i.e.,
1326 // we'll try to make the capacity smaller than it, not greater).
1327 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1328
1329 if (capacity_after_gc < minimum_desired_capacity) {
1330 // Don't expand unless it's significant
1331 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1332
1333 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1334 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1335 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1336 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1337
1338 expand(expand_bytes, _workers);
1339
1340 // No expansion, now see if we want to shrink
1341 } else if (capacity_after_gc > maximum_desired_capacity) {
1342 // Capacity too large, compute shrinking size
1343 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1344
1345 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1346 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1347 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1348 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1349
1350 shrink(shrink_bytes);
1351 }
1352 }
1353
1354 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1355 AllocationContext_t context,
1356 bool do_gc,
1357 bool clear_all_soft_refs,
1358 bool expect_null_mutator_alloc_region,
1359 bool* gc_succeeded) {
1360 *gc_succeeded = true;
1361 // Let's attempt the allocation first.
1362 HeapWord* result =
1363 attempt_allocation_at_safepoint(word_size,
1364 context,
1365 expect_null_mutator_alloc_region);
1366 if (result != NULL) {
1367 assert(*gc_succeeded, "sanity");
1368 return result;
1369 }
1370
1371 // In a G1 heap, we're supposed to keep allocation from failing by
1372 // incremental pauses. Therefore, at least for now, we'll favor
1373 // expansion over collection. (This might change in the future if we can
1374 // do something smarter than full collection to satisfy a failed alloc.)
1375 result = expand_and_allocate(word_size, context);
1376 if (result != NULL) {
1377 assert(*gc_succeeded, "sanity");
1378 return result;
1379 }
1380
1381 if (do_gc) {
1382 // Expansion didn't work, we'll try to do a Full GC.
1383 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1384 clear_all_soft_refs);
1385 }
1386
1387 return NULL;
1388 }
1389
1390 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1391 AllocationContext_t context,
1392 bool* succeeded) {
1393 assert_at_safepoint(true /* should_be_vm_thread */);
1394
1395 // Attempts to allocate followed by Full GC.
1396 HeapWord* result =
1397 satisfy_failed_allocation_helper(word_size,
1398 context,
1399 true, /* do_gc */
1400 false, /* clear_all_soft_refs */
1401 false, /* expect_null_mutator_alloc_region */
1402 succeeded);
1403
1404 if (result != NULL || !*succeeded) {
1405 return result;
1406 }
1407
1408 // Attempts to allocate followed by Full GC that will collect all soft references.
1409 result = satisfy_failed_allocation_helper(word_size,
1410 context,
1411 true, /* do_gc */
1412 true, /* clear_all_soft_refs */
1413 true, /* expect_null_mutator_alloc_region */
1414 succeeded);
1415
1416 if (result != NULL || !*succeeded) {
1417 return result;
1418 }
1419
1420 // Attempts to allocate, no GC
1421 result = satisfy_failed_allocation_helper(word_size,
1422 context,
1423 false, /* do_gc */
1424 false, /* clear_all_soft_refs */
1425 true, /* expect_null_mutator_alloc_region */
1426 succeeded);
1427
1428 if (result != NULL) {
1429 assert(*succeeded, "sanity");
1430 return result;
1431 }
1432
1433 assert(!collector_policy()->should_clear_all_soft_refs(),
1434 "Flag should have been handled and cleared prior to this point");
1435
1436 // What else? We might try synchronous finalization later. If the total
1437 // space available is large enough for the allocation, then a more
1438 // complete compaction phase than we've tried so far might be
1439 // appropriate.
1440 assert(*succeeded, "sanity");
1441 return NULL;
1442 }
1443
1444 // Attempting to expand the heap sufficiently
1445 // to support an allocation of the given "word_size". If
1446 // successful, perform the allocation and return the address of the
1447 // allocated block, or else "NULL".
1448
1449 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1450 assert_at_safepoint(true /* should_be_vm_thread */);
1451
1452 _verifier->verify_region_sets_optional();
1453
1454 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1455 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1456 word_size * HeapWordSize);
1457
1458
1459 if (expand(expand_bytes, _workers)) {
1460 _hrm.verify_optional();
1461 _verifier->verify_region_sets_optional();
1462 return attempt_allocation_at_safepoint(word_size,
1463 context,
1464 false /* expect_null_mutator_alloc_region */);
1465 }
1466 return NULL;
1467 }
1468
1469 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1470 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1471 aligned_expand_bytes = align_up(aligned_expand_bytes,
1472 HeapRegion::GrainBytes);
1473
1474 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1475 expand_bytes, aligned_expand_bytes);
1476
1477 if (is_maximal_no_gc()) {
1478 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1479 return false;
1480 }
1481
1482 double expand_heap_start_time_sec = os::elapsedTime();
1483 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1484 assert(regions_to_expand > 0, "Must expand by at least one region");
1485
1486 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1487 if (expand_time_ms != NULL) {
1488 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1489 }
1490
1491 if (expanded_by > 0) {
1492 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1493 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1494 g1_policy()->record_new_heap_size(num_regions());
1495 } else {
1496 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1497
1498 // The expansion of the virtual storage space was unsuccessful.
1499 // Let's see if it was because we ran out of swap.
1500 if (G1ExitOnExpansionFailure &&
1501 _hrm.available() >= regions_to_expand) {
1502 // We had head room...
1503 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1504 }
1505 }
1506 return regions_to_expand > 0;
1507 }
1508
1509 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1510 size_t aligned_shrink_bytes =
1511 ReservedSpace::page_align_size_down(shrink_bytes);
1512 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1513 HeapRegion::GrainBytes);
1514 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1515
1516 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1517 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1518
1519
1520 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1521 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1522 if (num_regions_removed > 0) {
1523 g1_policy()->record_new_heap_size(num_regions());
1524 } else {
1525 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1526 }
1527 }
1528
1529 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1530 _verifier->verify_region_sets_optional();
1531
1532 // We should only reach here at the end of a Full GC which means we
1533 // should not not be holding to any GC alloc regions. The method
1534 // below will make sure of that and do any remaining clean up.
1535 _allocator->abandon_gc_alloc_regions();
1536
1537 // Instead of tearing down / rebuilding the free lists here, we
1538 // could instead use the remove_all_pending() method on free_list to
1539 // remove only the ones that we need to remove.
1540 tear_down_region_sets(true /* free_list_only */);
1541 shrink_helper(shrink_bytes);
1542 rebuild_region_sets(true /* free_list_only */);
1543
1544 _hrm.verify_optional();
1545 _verifier->verify_region_sets_optional();
1546 }
1547
1548 // Public methods.
1549
1550 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1551 CollectedHeap(),
1552 _young_gen_sampling_thread(NULL),
1553 _collector_policy(collector_policy),
1554 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1555 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1556 _g1_policy(create_g1_policy(_gc_timer_stw)),
1557 _collection_set(this, _g1_policy),
1558 _dirty_card_queue_set(false),
1559 _is_alive_closure_cm(this),
1560 _is_alive_closure_stw(this),
1561 _ref_processor_cm(NULL),
1562 _ref_processor_stw(NULL),
1563 _bot(NULL),
1564 _hot_card_cache(NULL),
1565 _g1_rem_set(NULL),
1566 _cr(NULL),
1567 _g1mm(NULL),
1568 _preserved_marks_set(true /* in_c_heap */),
1569 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1570 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1571 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1572 _humongous_reclaim_candidates(),
1573 _has_humongous_reclaim_candidates(false),
1574 _archive_allocator(NULL),
1575 _free_regions_coming(false),
1576 _gc_time_stamp(0),
1577 _summary_bytes_used(0),
1578 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1579 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1580 _expand_heap_after_alloc_failure(true),
1581 _old_marking_cycles_started(0),
1582 _old_marking_cycles_completed(0),
1583 _in_cset_fast_test() {
1584
1585 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1586 /* are_GC_task_threads */true,
1587 /* are_ConcurrentGC_threads */false);
1588 _workers->initialize_workers();
1589 _verifier = new G1HeapVerifier(this);
1590
1591 _allocator = G1Allocator::create_allocator(this);
1592
1593 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1594
1595 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1596
1597 // Override the default _filler_array_max_size so that no humongous filler
1598 // objects are created.
1599 _filler_array_max_size = _humongous_object_threshold_in_words;
1600
1601 uint n_queues = ParallelGCThreads;
1602 _task_queues = new RefToScanQueueSet(n_queues);
1603
1604 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1605
1606 for (uint i = 0; i < n_queues; i++) {
1607 RefToScanQueue* q = new RefToScanQueue();
1608 q->initialize();
1609 _task_queues->register_queue(i, q);
1610 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1611 }
1612
1613 // Initialize the G1EvacuationFailureALot counters and flags.
1614 NOT_PRODUCT(reset_evacuation_should_fail();)
1615
1616 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1617 }
1618
1619 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1620 size_t size,
1621 size_t translation_factor) {
1622 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1623 // Allocate a new reserved space, preferring to use large pages.
1624 ReservedSpace rs(size, preferred_page_size);
1625 G1RegionToSpaceMapper* result =
1626 G1RegionToSpaceMapper::create_mapper(rs,
1627 size,
1628 rs.alignment(),
1629 HeapRegion::GrainBytes,
1630 translation_factor,
1631 mtGC);
1632
1633 os::trace_page_sizes_for_requested_size(description,
1634 size,
1635 preferred_page_size,
1636 rs.alignment(),
1637 rs.base(),
1638 rs.size());
1639
1640 return result;
1641 }
1642
1643 jint G1CollectedHeap::initialize_concurrent_refinement() {
1644 jint ecode = JNI_OK;
1645 _cr = G1ConcurrentRefine::create(&ecode);
1646 return ecode;
1647 }
1648
1649 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1650 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1651 if (_young_gen_sampling_thread->osthread() == NULL) {
1652 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1653 return JNI_ENOMEM;
1654 }
1655 return JNI_OK;
1656 }
1657
1658 jint G1CollectedHeap::initialize() {
1659 CollectedHeap::pre_initialize();
1660 os::enable_vtime();
1661
1662 // Necessary to satisfy locking discipline assertions.
1663
1664 MutexLocker x(Heap_lock);
1665
1666 // While there are no constraints in the GC code that HeapWordSize
1667 // be any particular value, there are multiple other areas in the
1668 // system which believe this to be true (e.g. oop->object_size in some
1669 // cases incorrectly returns the size in wordSize units rather than
1670 // HeapWordSize).
1671 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1672
1673 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1674 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1675 size_t heap_alignment = collector_policy()->heap_alignment();
1676
1677 // Ensure that the sizes are properly aligned.
1678 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1679 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1680 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1681
1682 // Reserve the maximum.
1683
1684 // When compressed oops are enabled, the preferred heap base
1685 // is calculated by subtracting the requested size from the
1686 // 32Gb boundary and using the result as the base address for
1687 // heap reservation. If the requested size is not aligned to
1688 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1689 // into the ReservedHeapSpace constructor) then the actual
1690 // base of the reserved heap may end up differing from the
1691 // address that was requested (i.e. the preferred heap base).
1692 // If this happens then we could end up using a non-optimal
1693 // compressed oops mode.
1694
1695 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1696 heap_alignment);
1697
1698 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1699
1700 // Create the barrier set for the entire reserved region.
1701 G1SATBCardTableLoggingModRefBS* bs
1702 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1703 bs->initialize();
1704 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1705 set_barrier_set(bs);
1706
1707 // Create the hot card cache.
1708 _hot_card_cache = new G1HotCardCache(this);
1709
1710 // Carve out the G1 part of the heap.
1711 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1712 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1713 G1RegionToSpaceMapper* heap_storage =
1714 G1RegionToSpaceMapper::create_mapper(g1_rs,
1715 g1_rs.size(),
1716 page_size,
1717 HeapRegion::GrainBytes,
1718 1,
1719 mtJavaHeap);
1720 os::trace_page_sizes("Heap",
1721 collector_policy()->min_heap_byte_size(),
1722 max_byte_size,
1723 page_size,
1724 heap_rs.base(),
1725 heap_rs.size());
1726 heap_storage->set_mapping_changed_listener(&_listener);
1727
1728 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1729 G1RegionToSpaceMapper* bot_storage =
1730 create_aux_memory_mapper("Block Offset Table",
1731 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1732 G1BlockOffsetTable::heap_map_factor());
1733
1734 G1RegionToSpaceMapper* cardtable_storage =
1735 create_aux_memory_mapper("Card Table",
1736 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1737 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1738
1739 G1RegionToSpaceMapper* card_counts_storage =
1740 create_aux_memory_mapper("Card Counts Table",
1741 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1742 G1CardCounts::heap_map_factor());
1743
1744 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1745 G1RegionToSpaceMapper* prev_bitmap_storage =
1746 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1747 G1RegionToSpaceMapper* next_bitmap_storage =
1748 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1749
1750 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1751 g1_barrier_set()->initialize(cardtable_storage);
1752 // Do later initialization work for concurrent refinement.
1753 _hot_card_cache->initialize(card_counts_storage);
1754
1755 // 6843694 - ensure that the maximum region index can fit
1756 // in the remembered set structures.
1757 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1758 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1759
1760 // Also create a G1 rem set.
1761 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1762 _g1_rem_set->initialize(max_capacity(), max_regions());
1763
1764 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1765 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1766 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1767 "too many cards per region");
1768
1769 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1770
1771 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1772
1773 {
1774 HeapWord* start = _hrm.reserved().start();
1775 HeapWord* end = _hrm.reserved().end();
1776 size_t granularity = HeapRegion::GrainBytes;
1777
1778 _in_cset_fast_test.initialize(start, end, granularity);
1779 _humongous_reclaim_candidates.initialize(start, end, granularity);
1780 }
1781
1782 // Create the G1ConcurrentMark data structure and thread.
1783 // (Must do this late, so that "max_regions" is defined.)
1784 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1785 if (_cm == NULL || !_cm->completed_initialization()) {
1786 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1787 return JNI_ENOMEM;
1788 }
1789 _cmThread = _cm->cm_thread();
1790
1791 // Now expand into the initial heap size.
1792 if (!expand(init_byte_size, _workers)) {
1793 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1794 return JNI_ENOMEM;
1795 }
1796
1797 // Perform any initialization actions delegated to the policy.
1798 g1_policy()->init(this, &_collection_set);
1799
1800 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1801 SATB_Q_FL_lock,
1802 G1SATBProcessCompletedThreshold,
1803 Shared_SATB_Q_lock);
1804
1805 jint ecode = initialize_concurrent_refinement();
1806 if (ecode != JNI_OK) {
1807 return ecode;
1808 }
1809
1810 ecode = initialize_young_gen_sampling_thread();
1811 if (ecode != JNI_OK) {
1812 return ecode;
1813 }
1814
1815 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1816 DirtyCardQ_FL_lock,
1817 (int)concurrent_refine()->yellow_zone(),
1818 (int)concurrent_refine()->red_zone(),
1819 Shared_DirtyCardQ_lock,
1820 NULL, // fl_owner
1821 true); // init_free_ids
1822
1823 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1824 DirtyCardQ_FL_lock,
1825 -1, // never trigger processing
1826 -1, // no limit on length
1827 Shared_DirtyCardQ_lock,
1828 &JavaThread::dirty_card_queue_set());
1829
1830 // Here we allocate the dummy HeapRegion that is required by the
1831 // G1AllocRegion class.
1832 HeapRegion* dummy_region = _hrm.get_dummy_region();
1833
1834 // We'll re-use the same region whether the alloc region will
1835 // require BOT updates or not and, if it doesn't, then a non-young
1836 // region will complain that it cannot support allocations without
1837 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1838 dummy_region->set_eden();
1839 // Make sure it's full.
1840 dummy_region->set_top(dummy_region->end());
1841 G1AllocRegion::setup(this, dummy_region);
1842
1843 _allocator->init_mutator_alloc_region();
1844
1845 // Do create of the monitoring and management support so that
1846 // values in the heap have been properly initialized.
1847 _g1mm = new G1MonitoringSupport(this);
1848
1849 G1StringDedup::initialize();
1850
1851 _preserved_marks_set.init(ParallelGCThreads);
1852
1853 _collection_set.initialize(max_regions());
1854
1855 return JNI_OK;
1856 }
1857
1858 void G1CollectedHeap::stop() {
1859 // Stop all concurrent threads. We do this to make sure these threads
1860 // do not continue to execute and access resources (e.g. logging)
1861 // that are destroyed during shutdown.
1862 _cr->stop();
1863 _young_gen_sampling_thread->stop();
1864 _cmThread->stop();
1865 if (G1StringDedup::is_enabled()) {
1866 G1StringDedup::stop();
1867 }
1868 }
1869
1870 void G1CollectedHeap::safepoint_synchronize_begin() {
1871 SuspendibleThreadSet::synchronize();
1872 }
1873
1874 void G1CollectedHeap::safepoint_synchronize_end() {
1875 SuspendibleThreadSet::desynchronize();
1876 }
1877
1878 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1879 return HeapRegion::max_region_size();
1880 }
1881
1882 void G1CollectedHeap::post_initialize() {
1883 ref_processing_init();
1884 }
1885
1886 void G1CollectedHeap::ref_processing_init() {
1887 // Reference processing in G1 currently works as follows:
1888 //
1889 // * There are two reference processor instances. One is
1890 // used to record and process discovered references
1891 // during concurrent marking; the other is used to
1892 // record and process references during STW pauses
1893 // (both full and incremental).
1894 // * Both ref processors need to 'span' the entire heap as
1895 // the regions in the collection set may be dotted around.
1896 //
1897 // * For the concurrent marking ref processor:
1898 // * Reference discovery is enabled at initial marking.
1899 // * Reference discovery is disabled and the discovered
1900 // references processed etc during remarking.
1901 // * Reference discovery is MT (see below).
1902 // * Reference discovery requires a barrier (see below).
1903 // * Reference processing may or may not be MT
1904 // (depending on the value of ParallelRefProcEnabled
1905 // and ParallelGCThreads).
1906 // * A full GC disables reference discovery by the CM
1907 // ref processor and abandons any entries on it's
1908 // discovered lists.
1909 //
1910 // * For the STW processor:
1911 // * Non MT discovery is enabled at the start of a full GC.
1912 // * Processing and enqueueing during a full GC is non-MT.
1913 // * During a full GC, references are processed after marking.
1914 //
1915 // * Discovery (may or may not be MT) is enabled at the start
1916 // of an incremental evacuation pause.
1917 // * References are processed near the end of a STW evacuation pause.
1918 // * For both types of GC:
1919 // * Discovery is atomic - i.e. not concurrent.
1920 // * Reference discovery will not need a barrier.
1921
1922 MemRegion mr = reserved_region();
1923
1924 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1925
1926 // Concurrent Mark ref processor
1927 _ref_processor_cm =
1928 new ReferenceProcessor(mr, // span
1929 mt_processing,
1930 // mt processing
1931 ParallelGCThreads,
1932 // degree of mt processing
1933 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1934 // mt discovery
1935 MAX2(ParallelGCThreads, ConcGCThreads),
1936 // degree of mt discovery
1937 false,
1938 // Reference discovery is not atomic
1939 &_is_alive_closure_cm);
1940 // is alive closure
1941 // (for efficiency/performance)
1942
1943 // STW ref processor
1944 _ref_processor_stw =
1945 new ReferenceProcessor(mr, // span
1946 mt_processing,
1947 // mt processing
1948 ParallelGCThreads,
1949 // degree of mt processing
1950 (ParallelGCThreads > 1),
1951 // mt discovery
1952 ParallelGCThreads,
1953 // degree of mt discovery
1954 true,
1955 // Reference discovery is atomic
1956 &_is_alive_closure_stw);
1957 // is alive closure
1958 // (for efficiency/performance)
1959 }
1960
1961 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1962 return _collector_policy;
1963 }
1964
1965 size_t G1CollectedHeap::capacity() const {
1966 return _hrm.length() * HeapRegion::GrainBytes;
1967 }
1968
1969 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1970 return _hrm.total_free_bytes();
1971 }
1972
1973 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1974 hr->reset_gc_time_stamp();
1975 }
1976
1977 #ifndef PRODUCT
1978
1979 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1980 private:
1981 unsigned _gc_time_stamp;
1982 bool _failures;
1983
1984 public:
1985 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1986 _gc_time_stamp(gc_time_stamp), _failures(false) { }
1987
1988 virtual bool doHeapRegion(HeapRegion* hr) {
1989 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1990 if (_gc_time_stamp != region_gc_time_stamp) {
1991 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1992 region_gc_time_stamp, _gc_time_stamp);
1993 _failures = true;
1994 }
1995 return false;
1996 }
1997
1998 bool failures() { return _failures; }
1999 };
2000
2001 void G1CollectedHeap::check_gc_time_stamps() {
2002 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2003 heap_region_iterate(&cl);
2004 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2005 }
2006 #endif // PRODUCT
2007
2008 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2009 _hot_card_cache->drain(cl, worker_i);
2010 }
2011
2012 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2013 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2014 size_t n_completed_buffers = 0;
2015 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
2016 n_completed_buffers++;
2017 }
2018 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2019 dcqs.clear_n_completed_buffers();
2020 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2021 }
2022
2023 // Computes the sum of the storage used by the various regions.
2024 size_t G1CollectedHeap::used() const {
2025 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2026 if (_archive_allocator != NULL) {
2027 result += _archive_allocator->used();
2028 }
2029 return result;
2030 }
2031
2032 size_t G1CollectedHeap::used_unlocked() const {
2033 return _summary_bytes_used;
2034 }
2035
2036 class SumUsedClosure: public HeapRegionClosure {
2037 size_t _used;
2038 public:
2039 SumUsedClosure() : _used(0) {}
2040 bool doHeapRegion(HeapRegion* r) {
2041 _used += r->used();
2042 return false;
2043 }
2044 size_t result() { return _used; }
2045 };
2046
2047 size_t G1CollectedHeap::recalculate_used() const {
2048 double recalculate_used_start = os::elapsedTime();
2049
2050 SumUsedClosure blk;
2051 heap_region_iterate(&blk);
2052
2053 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2054 return blk.result();
2055 }
2056
2057 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2058 switch (cause) {
2059 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2060 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2061 case GCCause::_update_allocation_context_stats_inc: return true;
2062 case GCCause::_wb_conc_mark: return true;
2063 default : return false;
2064 }
2065 }
2066
2067 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2068 switch (cause) {
2069 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2070 case GCCause::_g1_humongous_allocation: return true;
2071 default: return is_user_requested_concurrent_full_gc(cause);
2072 }
2073 }
2074
2075 #ifndef PRODUCT
2076 void G1CollectedHeap::allocate_dummy_regions() {
2077 // Let's fill up most of the region
2078 size_t word_size = HeapRegion::GrainWords - 1024;
2079 // And as a result the region we'll allocate will be humongous.
2080 guarantee(is_humongous(word_size), "sanity");
2081
2082 // _filler_array_max_size is set to humongous object threshold
2083 // but temporarily change it to use CollectedHeap::fill_with_object().
2084 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2085
2086 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2087 // Let's use the existing mechanism for the allocation
2088 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2089 AllocationContext::system());
2090 if (dummy_obj != NULL) {
2091 MemRegion mr(dummy_obj, word_size);
2092 CollectedHeap::fill_with_object(mr);
2093 } else {
2094 // If we can't allocate once, we probably cannot allocate
2095 // again. Let's get out of the loop.
2096 break;
2097 }
2098 }
2099 }
2100 #endif // !PRODUCT
2101
2102 void G1CollectedHeap::increment_old_marking_cycles_started() {
2103 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2104 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2105 "Wrong marking cycle count (started: %d, completed: %d)",
2106 _old_marking_cycles_started, _old_marking_cycles_completed);
2107
2108 _old_marking_cycles_started++;
2109 }
2110
2111 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2112 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2113
2114 // We assume that if concurrent == true, then the caller is a
2115 // concurrent thread that was joined the Suspendible Thread
2116 // Set. If there's ever a cheap way to check this, we should add an
2117 // assert here.
2118
2119 // Given that this method is called at the end of a Full GC or of a
2120 // concurrent cycle, and those can be nested (i.e., a Full GC can
2121 // interrupt a concurrent cycle), the number of full collections
2122 // completed should be either one (in the case where there was no
2123 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2124 // behind the number of full collections started.
2125
2126 // This is the case for the inner caller, i.e. a Full GC.
2127 assert(concurrent ||
2128 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2129 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2130 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2131 "is inconsistent with _old_marking_cycles_completed = %u",
2132 _old_marking_cycles_started, _old_marking_cycles_completed);
2133
2134 // This is the case for the outer caller, i.e. the concurrent cycle.
2135 assert(!concurrent ||
2136 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2137 "for outer caller (concurrent cycle): "
2138 "_old_marking_cycles_started = %u "
2139 "is inconsistent with _old_marking_cycles_completed = %u",
2140 _old_marking_cycles_started, _old_marking_cycles_completed);
2141
2142 _old_marking_cycles_completed += 1;
2143
2144 // We need to clear the "in_progress" flag in the CM thread before
2145 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2146 // is set) so that if a waiter requests another System.gc() it doesn't
2147 // incorrectly see that a marking cycle is still in progress.
2148 if (concurrent) {
2149 _cmThread->set_idle();
2150 }
2151
2152 // This notify_all() will ensure that a thread that called
2153 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2154 // and it's waiting for a full GC to finish will be woken up. It is
2155 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2156 FullGCCount_lock->notify_all();
2157 }
2158
2159 void G1CollectedHeap::collect(GCCause::Cause cause) {
2160 assert_heap_not_locked();
2161
2162 uint gc_count_before;
2163 uint old_marking_count_before;
2164 uint full_gc_count_before;
2165 bool retry_gc;
2166
2167 do {
2168 retry_gc = false;
2169
2170 {
2171 MutexLocker ml(Heap_lock);
2172
2173 // Read the GC count while holding the Heap_lock
2174 gc_count_before = total_collections();
2175 full_gc_count_before = total_full_collections();
2176 old_marking_count_before = _old_marking_cycles_started;
2177 }
2178
2179 if (should_do_concurrent_full_gc(cause)) {
2180 // Schedule an initial-mark evacuation pause that will start a
2181 // concurrent cycle. We're setting word_size to 0 which means that
2182 // we are not requesting a post-GC allocation.
2183 VM_G1IncCollectionPause op(gc_count_before,
2184 0, /* word_size */
2185 true, /* should_initiate_conc_mark */
2186 g1_policy()->max_pause_time_ms(),
2187 cause);
2188 op.set_allocation_context(AllocationContext::current());
2189
2190 VMThread::execute(&op);
2191 if (!op.pause_succeeded()) {
2192 if (old_marking_count_before == _old_marking_cycles_started) {
2193 retry_gc = op.should_retry_gc();
2194 } else {
2195 // A Full GC happened while we were trying to schedule the
2196 // initial-mark GC. No point in starting a new cycle given
2197 // that the whole heap was collected anyway.
2198 }
2199
2200 if (retry_gc) {
2201 if (GCLocker::is_active_and_needs_gc()) {
2202 GCLocker::stall_until_clear();
2203 }
2204 }
2205 }
2206 } else {
2207 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2208 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2209
2210 // Schedule a standard evacuation pause. We're setting word_size
2211 // to 0 which means that we are not requesting a post-GC allocation.
2212 VM_G1IncCollectionPause op(gc_count_before,
2213 0, /* word_size */
2214 false, /* should_initiate_conc_mark */
2215 g1_policy()->max_pause_time_ms(),
2216 cause);
2217 VMThread::execute(&op);
2218 } else {
2219 // Schedule a Full GC.
2220 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2221 VMThread::execute(&op);
2222 }
2223 }
2224 } while (retry_gc);
2225 }
2226
2227 bool G1CollectedHeap::is_in(const void* p) const {
2228 if (_hrm.reserved().contains(p)) {
2229 // Given that we know that p is in the reserved space,
2230 // heap_region_containing() should successfully
2231 // return the containing region.
2232 HeapRegion* hr = heap_region_containing(p);
2233 return hr->is_in(p);
2234 } else {
2235 return false;
2236 }
2237 }
2238
2239 #ifdef ASSERT
2240 bool G1CollectedHeap::is_in_exact(const void* p) const {
2241 bool contains = reserved_region().contains(p);
2242 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2243 if (contains && available) {
2244 return true;
2245 } else {
2246 return false;
2247 }
2248 }
2249 #endif
2250
2251 // Iteration functions.
2252
2253 // Iterates an ObjectClosure over all objects within a HeapRegion.
2254
2255 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2256 ObjectClosure* _cl;
2257 public:
2258 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2259 bool doHeapRegion(HeapRegion* r) {
2260 if (!r->is_continues_humongous()) {
2261 r->object_iterate(_cl);
2262 }
2263 return false;
2264 }
2265 };
2266
2267 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2268 IterateObjectClosureRegionClosure blk(cl);
2269 heap_region_iterate(&blk);
2270 }
2271
2272 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2273 _hrm.iterate(cl);
2274 }
2275
2276 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2277 HeapRegionClaimer *hrclaimer,
2278 uint worker_id) const {
2279 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2280 }
2281
2282 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2283 HeapRegionClaimer *hrclaimer) const {
2284 _hrm.par_iterate(cl, hrclaimer, 0);
2285 }
2286
2287 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2288 _collection_set.iterate(cl);
2289 }
2290
2291 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2292 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2293 }
2294
2295 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2296 HeapRegion* hr = heap_region_containing(addr);
2297 return hr->block_start(addr);
2298 }
2299
2300 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2301 HeapRegion* hr = heap_region_containing(addr);
2302 return hr->block_size(addr);
2303 }
2304
2305 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2306 HeapRegion* hr = heap_region_containing(addr);
2307 return hr->block_is_obj(addr);
2308 }
2309
2310 bool G1CollectedHeap::supports_tlab_allocation() const {
2311 return true;
2312 }
2313
2314 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2315 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2316 }
2317
2318 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2319 return _eden.length() * HeapRegion::GrainBytes;
2320 }
2321
2322 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2323 // must be equal to the humongous object limit.
2324 size_t G1CollectedHeap::max_tlab_size() const {
2325 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2326 }
2327
2328 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2329 AllocationContext_t context = AllocationContext::current();
2330 return _allocator->unsafe_max_tlab_alloc(context);
2331 }
2332
2333 size_t G1CollectedHeap::max_capacity() const {
2334 return _hrm.reserved().byte_size();
2335 }
2336
2337 jlong G1CollectedHeap::millis_since_last_gc() {
2338 // See the notes in GenCollectedHeap::millis_since_last_gc()
2339 // for more information about the implementation.
2340 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2341 _g1_policy->collection_pause_end_millis();
2342 if (ret_val < 0) {
2343 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2344 ". returning zero instead.", ret_val);
2345 return 0;
2346 }
2347 return ret_val;
2348 }
2349
2350 void G1CollectedHeap::prepare_for_verify() {
2351 _verifier->prepare_for_verify();
2352 }
2353
2354 void G1CollectedHeap::verify(VerifyOption vo) {
2355 _verifier->verify(vo);
2356 }
2357
2358 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2359 return true;
2360 }
2361
2362 const char* const* G1CollectedHeap::concurrent_phases() const {
2363 return _cmThread->concurrent_phases();
2364 }
2365
2366 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2367 return _cmThread->request_concurrent_phase(phase);
2368 }
2369
2370 class PrintRegionClosure: public HeapRegionClosure {
2371 outputStream* _st;
2372 public:
2373 PrintRegionClosure(outputStream* st) : _st(st) {}
2374 bool doHeapRegion(HeapRegion* r) {
2375 r->print_on(_st);
2376 return false;
2377 }
2378 };
2379
2380 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2381 const HeapRegion* hr,
2382 const VerifyOption vo) const {
2383 switch (vo) {
2384 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2385 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2386 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2387 default: ShouldNotReachHere();
2388 }
2389 return false; // keep some compilers happy
2390 }
2391
2392 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2393 const VerifyOption vo) const {
2394 switch (vo) {
2395 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2396 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2397 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2398 default: ShouldNotReachHere();
2399 }
2400 return false; // keep some compilers happy
2401 }
2402
2403 void G1CollectedHeap::print_heap_regions() const {
2404 LogTarget(Trace, gc, heap, region) lt;
2405 if (lt.is_enabled()) {
2406 LogStream ls(lt);
2407 print_regions_on(&ls);
2408 }
2409 }
2410
2411 void G1CollectedHeap::print_on(outputStream* st) const {
2412 st->print(" %-20s", "garbage-first heap");
2413 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2414 capacity()/K, used_unlocked()/K);
2415 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2416 p2i(_hrm.reserved().start()),
2417 p2i(_hrm.reserved().end()));
2418 st->cr();
2419 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2420 uint young_regions = young_regions_count();
2421 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2422 (size_t) young_regions * HeapRegion::GrainBytes / K);
2423 uint survivor_regions = survivor_regions_count();
2424 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2425 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2426 st->cr();
2427 MetaspaceAux::print_on(st);
2428 }
2429
2430 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2431 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2432 "HS=humongous(starts), HC=humongous(continues), "
2433 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2434 "AC=allocation context, "
2435 "TAMS=top-at-mark-start (previous, next)");
2436 PrintRegionClosure blk(st);
2437 heap_region_iterate(&blk);
2438 }
2439
2440 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2441 print_on(st);
2442
2443 // Print the per-region information.
2444 print_regions_on(st);
2445 }
2446
2447 void G1CollectedHeap::print_on_error(outputStream* st) const {
2448 this->CollectedHeap::print_on_error(st);
2449
2450 if (_cm != NULL) {
2451 st->cr();
2452 _cm->print_on_error(st);
2453 }
2454 }
2455
2456 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2457 workers()->print_worker_threads_on(st);
2458 _cmThread->print_on(st);
2459 st->cr();
2460 _cm->print_worker_threads_on(st);
2461 _cr->print_threads_on(st);
2462 _young_gen_sampling_thread->print_on(st);
2463 if (G1StringDedup::is_enabled()) {
2464 G1StringDedup::print_worker_threads_on(st);
2465 }
2466 }
2467
2468 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2469 workers()->threads_do(tc);
2470 tc->do_thread(_cmThread);
2471 _cm->threads_do(tc);
2472 _cr->threads_do(tc);
2473 tc->do_thread(_young_gen_sampling_thread);
2474 if (G1StringDedup::is_enabled()) {
2475 G1StringDedup::threads_do(tc);
2476 }
2477 }
2478
2479 void G1CollectedHeap::print_tracing_info() const {
2480 g1_rem_set()->print_summary_info();
2481 concurrent_mark()->print_summary_info();
2482 }
2483
2484 #ifndef PRODUCT
2485 // Helpful for debugging RSet issues.
2486
2487 class PrintRSetsClosure : public HeapRegionClosure {
2488 private:
2489 const char* _msg;
2490 size_t _occupied_sum;
2491
2492 public:
2493 bool doHeapRegion(HeapRegion* r) {
2494 HeapRegionRemSet* hrrs = r->rem_set();
2495 size_t occupied = hrrs->occupied();
2496 _occupied_sum += occupied;
2497
2498 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2499 if (occupied == 0) {
2500 tty->print_cr(" RSet is empty");
2501 } else {
2502 hrrs->print();
2503 }
2504 tty->print_cr("----------");
2505 return false;
2506 }
2507
2508 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2509 tty->cr();
2510 tty->print_cr("========================================");
2511 tty->print_cr("%s", msg);
2512 tty->cr();
2513 }
2514
2515 ~PrintRSetsClosure() {
2516 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2517 tty->print_cr("========================================");
2518 tty->cr();
2519 }
2520 };
2521
2522 void G1CollectedHeap::print_cset_rsets() {
2523 PrintRSetsClosure cl("Printing CSet RSets");
2524 collection_set_iterate(&cl);
2525 }
2526
2527 void G1CollectedHeap::print_all_rsets() {
2528 PrintRSetsClosure cl("Printing All RSets");;
2529 heap_region_iterate(&cl);
2530 }
2531 #endif // PRODUCT
2532
2533 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2534
2535 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2536 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2537 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2538
2539 size_t eden_capacity_bytes =
2540 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2541
2542 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2543 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2544 eden_capacity_bytes, survivor_used_bytes, num_regions());
2545 }
2546
2547 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2548 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2549 stats->unused(), stats->used(), stats->region_end_waste(),
2550 stats->regions_filled(), stats->direct_allocated(),
2551 stats->failure_used(), stats->failure_waste());
2552 }
2553
2554 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2555 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2556 gc_tracer->report_gc_heap_summary(when, heap_summary);
2557
2558 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2559 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2560 }
2561
2562 G1CollectedHeap* G1CollectedHeap::heap() {
2563 CollectedHeap* heap = Universe::heap();
2564 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2565 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2566 return (G1CollectedHeap*)heap;
2567 }
2568
2569 void G1CollectedHeap::gc_prologue(bool full) {
2570 // always_do_update_barrier = false;
2571 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2572
2573 // This summary needs to be printed before incrementing total collections.
2574 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2575
2576 // Update common counters.
2577 increment_total_collections(full /* full gc */);
2578 if (full) {
2579 increment_old_marking_cycles_started();
2580 reset_gc_time_stamp();
2581 } else {
2582 increment_gc_time_stamp();
2583 }
2584
2585 // Fill TLAB's and such
2586 double start = os::elapsedTime();
2587 accumulate_statistics_all_tlabs();
2588 ensure_parsability(true);
2589 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2590 }
2591
2592 void G1CollectedHeap::gc_epilogue(bool full) {
2593 // Update common counters.
2594 if (full) {
2595 // Update the number of full collections that have been completed.
2596 increment_old_marking_cycles_completed(false /* concurrent */);
2597 }
2598
2599 // We are at the end of the GC. Total collections has already been increased.
2600 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2601
2602 // FIXME: what is this about?
2603 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2604 // is set.
2605 #if COMPILER2_OR_JVMCI
2606 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2607 #endif
2608 // always_do_update_barrier = true;
2609
2610 double start = os::elapsedTime();
2611 resize_all_tlabs();
2612 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2613
2614 allocation_context_stats().update(full);
2615
2616 MemoryService::track_memory_usage();
2617 // We have just completed a GC. Update the soft reference
2618 // policy with the new heap occupancy
2619 Universe::update_heap_info_at_gc();
2620 }
2621
2622 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2623 uint gc_count_before,
2624 bool* succeeded,
2625 GCCause::Cause gc_cause) {
2626 assert_heap_not_locked_and_not_at_safepoint();
2627 VM_G1IncCollectionPause op(gc_count_before,
2628 word_size,
2629 false, /* should_initiate_conc_mark */
2630 g1_policy()->max_pause_time_ms(),
2631 gc_cause);
2632
2633 op.set_allocation_context(AllocationContext::current());
2634 VMThread::execute(&op);
2635
2636 HeapWord* result = op.result();
2637 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2638 assert(result == NULL || ret_succeeded,
2639 "the result should be NULL if the VM did not succeed");
2640 *succeeded = ret_succeeded;
2641
2642 assert_heap_not_locked();
2643 return result;
2644 }
2645
2646 void
2647 G1CollectedHeap::doConcurrentMark() {
2648 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2649 if (!_cmThread->in_progress()) {
2650 _cmThread->set_started();
2651 CGC_lock->notify();
2652 }
2653 }
2654
2655 size_t G1CollectedHeap::pending_card_num() {
2656 size_t extra_cards = 0;
2657 JavaThread *curr = Threads::first();
2658 while (curr != NULL) {
2659 DirtyCardQueue& dcq = curr->dirty_card_queue();
2660 extra_cards += dcq.size();
2661 curr = curr->next();
2662 }
2663 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2664 size_t buffer_size = dcqs.buffer_size();
2665 size_t buffer_num = dcqs.completed_buffers_num();
2666
2667 return buffer_size * buffer_num + extra_cards;
2668 }
2669
2670 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2671 private:
2672 size_t _total_humongous;
2673 size_t _candidate_humongous;
2674
2675 DirtyCardQueue _dcq;
2676
2677 // We don't nominate objects with many remembered set entries, on
2678 // the assumption that such objects are likely still live.
2679 bool is_remset_small(HeapRegion* region) const {
2680 HeapRegionRemSet* const rset = region->rem_set();
2681 return G1EagerReclaimHumongousObjectsWithStaleRefs
2682 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2683 : rset->is_empty();
2684 }
2685
2686 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2687 assert(region->is_starts_humongous(), "Must start a humongous object");
2688
2689 oop obj = oop(region->bottom());
2690
2691 // Dead objects cannot be eager reclaim candidates. Due to class
2692 // unloading it is unsafe to query their classes so we return early.
2693 if (heap->is_obj_dead(obj, region)) {
2694 return false;
2695 }
2696
2697 // Candidate selection must satisfy the following constraints
2698 // while concurrent marking is in progress:
2699 //
2700 // * In order to maintain SATB invariants, an object must not be
2701 // reclaimed if it was allocated before the start of marking and
2702 // has not had its references scanned. Such an object must have
2703 // its references (including type metadata) scanned to ensure no
2704 // live objects are missed by the marking process. Objects
2705 // allocated after the start of concurrent marking don't need to
2706 // be scanned.
2707 //
2708 // * An object must not be reclaimed if it is on the concurrent
2709 // mark stack. Objects allocated after the start of concurrent
2710 // marking are never pushed on the mark stack.
2711 //
2712 // Nominating only objects allocated after the start of concurrent
2713 // marking is sufficient to meet both constraints. This may miss
2714 // some objects that satisfy the constraints, but the marking data
2715 // structures don't support efficiently performing the needed
2716 // additional tests or scrubbing of the mark stack.
2717 //
2718 // However, we presently only nominate is_typeArray() objects.
2719 // A humongous object containing references induces remembered
2720 // set entries on other regions. In order to reclaim such an
2721 // object, those remembered sets would need to be cleaned up.
2722 //
2723 // We also treat is_typeArray() objects specially, allowing them
2724 // to be reclaimed even if allocated before the start of
2725 // concurrent mark. For this we rely on mark stack insertion to
2726 // exclude is_typeArray() objects, preventing reclaiming an object
2727 // that is in the mark stack. We also rely on the metadata for
2728 // such objects to be built-in and so ensured to be kept live.
2729 // Frequent allocation and drop of large binary blobs is an
2730 // important use case for eager reclaim, and this special handling
2731 // may reduce needed headroom.
2732
2733 return obj->is_typeArray() && is_remset_small(region);
2734 }
2735
2736 public:
2737 RegisterHumongousWithInCSetFastTestClosure()
2738 : _total_humongous(0),
2739 _candidate_humongous(0),
2740 _dcq(&JavaThread::dirty_card_queue_set()) {
2741 }
2742
2743 virtual bool doHeapRegion(HeapRegion* r) {
2744 if (!r->is_starts_humongous()) {
2745 return false;
2746 }
2747 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2748
2749 bool is_candidate = humongous_region_is_candidate(g1h, r);
2750 uint rindex = r->hrm_index();
2751 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2752 if (is_candidate) {
2753 _candidate_humongous++;
2754 g1h->register_humongous_region_with_cset(rindex);
2755 // Is_candidate already filters out humongous object with large remembered sets.
2756 // If we have a humongous object with a few remembered sets, we simply flush these
2757 // remembered set entries into the DCQS. That will result in automatic
2758 // re-evaluation of their remembered set entries during the following evacuation
2759 // phase.
2760 if (!r->rem_set()->is_empty()) {
2761 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2762 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2763 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2764 HeapRegionRemSetIterator hrrs(r->rem_set());
2765 size_t card_index;
2766 while (hrrs.has_next(card_index)) {
2767 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2768 // The remembered set might contain references to already freed
2769 // regions. Filter out such entries to avoid failing card table
2770 // verification.
2771 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2772 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2773 *card_ptr = CardTableModRefBS::dirty_card_val();
2774 _dcq.enqueue(card_ptr);
2775 }
2776 }
2777 }
2778 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2779 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2780 hrrs.n_yielded(), r->rem_set()->occupied());
2781 r->rem_set()->clear_locked();
2782 }
2783 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2784 }
2785 _total_humongous++;
2786
2787 return false;
2788 }
2789
2790 size_t total_humongous() const { return _total_humongous; }
2791 size_t candidate_humongous() const { return _candidate_humongous; }
2792
2793 void flush_rem_set_entries() { _dcq.flush(); }
2794 };
2795
2796 void G1CollectedHeap::register_humongous_regions_with_cset() {
2797 if (!G1EagerReclaimHumongousObjects) {
2798 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2799 return;
2800 }
2801 double time = os::elapsed_counter();
2802
2803 // Collect reclaim candidate information and register candidates with cset.
2804 RegisterHumongousWithInCSetFastTestClosure cl;
2805 heap_region_iterate(&cl);
2806
2807 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2808 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2809 cl.total_humongous(),
2810 cl.candidate_humongous());
2811 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2812
2813 // Finally flush all remembered set entries to re-check into the global DCQS.
2814 cl.flush_rem_set_entries();
2815 }
2816
2817 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2818 public:
2819 bool doHeapRegion(HeapRegion* hr) {
2820 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2821 hr->verify_rem_set();
2822 }
2823 return false;
2824 }
2825 };
2826
2827 uint G1CollectedHeap::num_task_queues() const {
2828 return _task_queues->size();
2829 }
2830
2831 #if TASKQUEUE_STATS
2832 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2833 st->print_raw_cr("GC Task Stats");
2834 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2835 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2836 }
2837
2838 void G1CollectedHeap::print_taskqueue_stats() const {
2839 if (!log_is_enabled(Trace, gc, task, stats)) {
2840 return;
2841 }
2842 Log(gc, task, stats) log;
2843 ResourceMark rm;
2844 LogStream ls(log.trace());
2845 outputStream* st = &ls;
2846
2847 print_taskqueue_stats_hdr(st);
2848
2849 TaskQueueStats totals;
2850 const uint n = num_task_queues();
2851 for (uint i = 0; i < n; ++i) {
2852 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2853 totals += task_queue(i)->stats;
2854 }
2855 st->print_raw("tot "); totals.print(st); st->cr();
2856
2857 DEBUG_ONLY(totals.verify());
2858 }
2859
2860 void G1CollectedHeap::reset_taskqueue_stats() {
2861 const uint n = num_task_queues();
2862 for (uint i = 0; i < n; ++i) {
2863 task_queue(i)->stats.reset();
2864 }
2865 }
2866 #endif // TASKQUEUE_STATS
2867
2868 void G1CollectedHeap::wait_for_root_region_scanning() {
2869 double scan_wait_start = os::elapsedTime();
2870 // We have to wait until the CM threads finish scanning the
2871 // root regions as it's the only way to ensure that all the
2872 // objects on them have been correctly scanned before we start
2873 // moving them during the GC.
2874 bool waited = _cm->root_regions()->wait_until_scan_finished();
2875 double wait_time_ms = 0.0;
2876 if (waited) {
2877 double scan_wait_end = os::elapsedTime();
2878 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2879 }
2880 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2881 }
2882
2883 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2884 private:
2885 G1HRPrinter* _hr_printer;
2886 public:
2887 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2888
2889 virtual bool doHeapRegion(HeapRegion* r) {
2890 _hr_printer->cset(r);
2891 return false;
2892 }
2893 };
2894
2895 void G1CollectedHeap::start_new_collection_set() {
2896 collection_set()->start_incremental_building();
2897
2898 clear_cset_fast_test();
2899
2900 guarantee(_eden.length() == 0, "eden should have been cleared");
2901 g1_policy()->transfer_survivors_to_cset(survivor());
2902 }
2903
2904 bool
2905 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2906 assert_at_safepoint(true /* should_be_vm_thread */);
2907 guarantee(!is_gc_active(), "collection is not reentrant");
2908
2909 if (GCLocker::check_active_before_gc()) {
2910 return false;
2911 }
2912
2913 _gc_timer_stw->register_gc_start();
2914
2915 GCIdMark gc_id_mark;
2916 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2917
2918 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2919 ResourceMark rm;
2920
2921 g1_policy()->note_gc_start();
2922
2923 wait_for_root_region_scanning();
2924
2925 print_heap_before_gc();
2926 print_heap_regions();
2927 trace_heap_before_gc(_gc_tracer_stw);
2928
2929 _verifier->verify_region_sets_optional();
2930 _verifier->verify_dirty_young_regions();
2931
2932 // We should not be doing initial mark unless the conc mark thread is running
2933 if (!_cmThread->should_terminate()) {
2934 // This call will decide whether this pause is an initial-mark
2935 // pause. If it is, during_initial_mark_pause() will return true
2936 // for the duration of this pause.
2937 g1_policy()->decide_on_conc_mark_initiation();
2938 }
2939
2940 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2941 assert(!collector_state()->during_initial_mark_pause() ||
2942 collector_state()->gcs_are_young(), "sanity");
2943
2944 // We also do not allow mixed GCs during marking.
2945 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2946
2947 // Record whether this pause is an initial mark. When the current
2948 // thread has completed its logging output and it's safe to signal
2949 // the CM thread, the flag's value in the policy has been reset.
2950 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2951
2952 // Inner scope for scope based logging, timers, and stats collection
2953 {
2954 EvacuationInfo evacuation_info;
2955
2956 if (collector_state()->during_initial_mark_pause()) {
2957 // We are about to start a marking cycle, so we increment the
2958 // full collection counter.
2959 increment_old_marking_cycles_started();
2960 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2961 }
2962
2963 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2964
2965 GCTraceCPUTime tcpu;
2966
2967 FormatBuffer<> gc_string("Pause ");
2968 if (collector_state()->during_initial_mark_pause()) {
2969 gc_string.append("Initial Mark");
2970 } else if (collector_state()->gcs_are_young()) {
2971 gc_string.append("Young");
2972 } else {
2973 gc_string.append("Mixed");
2974 }
2975 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2976
2977 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2978 workers()->active_workers(),
2979 Threads::number_of_non_daemon_threads());
2980 workers()->update_active_workers(active_workers);
2981 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2982
2983 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2984 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
2985
2986 // If the secondary_free_list is not empty, append it to the
2987 // free_list. No need to wait for the cleanup operation to finish;
2988 // the region allocation code will check the secondary_free_list
2989 // and wait if necessary. If the G1StressConcRegionFreeing flag is
2990 // set, skip this step so that the region allocation code has to
2991 // get entries from the secondary_free_list.
2992 if (!G1StressConcRegionFreeing) {
2993 append_secondary_free_list_if_not_empty_with_lock();
2994 }
2995
2996 G1HeapTransition heap_transition(this);
2997 size_t heap_used_bytes_before_gc = used();
2998
2999 // Don't dynamically change the number of GC threads this early. A value of
3000 // 0 is used to indicate serial work. When parallel work is done,
3001 // it will be set.
3002
3003 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3004 IsGCActiveMark x;
3005
3006 gc_prologue(false);
3007
3008 if (VerifyRememberedSets) {
3009 log_info(gc, verify)("[Verifying RemSets before GC]");
3010 VerifyRegionRemSetClosure v_cl;
3011 heap_region_iterate(&v_cl);
3012 }
3013
3014 _verifier->verify_before_gc();
3015
3016 _verifier->check_bitmaps("GC Start");
3017
3018 #if COMPILER2_OR_JVMCI
3019 DerivedPointerTable::clear();
3020 #endif
3021
3022 // Please see comment in g1CollectedHeap.hpp and
3023 // G1CollectedHeap::ref_processing_init() to see how
3024 // reference processing currently works in G1.
3025
3026 // Enable discovery in the STW reference processor
3027 if (g1_policy()->should_process_references()) {
3028 ref_processor_stw()->enable_discovery();
3029 } else {
3030 ref_processor_stw()->disable_discovery();
3031 }
3032
3033 {
3034 // We want to temporarily turn off discovery by the
3035 // CM ref processor, if necessary, and turn it back on
3036 // on again later if we do. Using a scoped
3037 // NoRefDiscovery object will do this.
3038 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3039
3040 // Forget the current alloc region (we might even choose it to be part
3041 // of the collection set!).
3042 _allocator->release_mutator_alloc_region();
3043
3044 // This timing is only used by the ergonomics to handle our pause target.
3045 // It is unclear why this should not include the full pause. We will
3046 // investigate this in CR 7178365.
3047 //
3048 // Preserving the old comment here if that helps the investigation:
3049 //
3050 // The elapsed time induced by the start time below deliberately elides
3051 // the possible verification above.
3052 double sample_start_time_sec = os::elapsedTime();
3053
3054 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3055
3056 if (collector_state()->during_initial_mark_pause()) {
3057 concurrent_mark()->checkpoint_roots_initial_pre();
3058 }
3059
3060 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3061
3062 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3063
3064 // Make sure the remembered sets are up to date. This needs to be
3065 // done before register_humongous_regions_with_cset(), because the
3066 // remembered sets are used there to choose eager reclaim candidates.
3067 // If the remembered sets are not up to date we might miss some
3068 // entries that need to be handled.
3069 g1_rem_set()->cleanupHRRS();
3070
3071 register_humongous_regions_with_cset();
3072
3073 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3074
3075 // We call this after finalize_cset() to
3076 // ensure that the CSet has been finalized.
3077 _cm->verify_no_cset_oops();
3078
3079 if (_hr_printer.is_active()) {
3080 G1PrintCollectionSetClosure cl(&_hr_printer);
3081 _collection_set.iterate(&cl);
3082 }
3083
3084 // Initialize the GC alloc regions.
3085 _allocator->init_gc_alloc_regions(evacuation_info);
3086
3087 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3088 pre_evacuate_collection_set();
3089
3090 // Actually do the work...
3091 evacuate_collection_set(evacuation_info, &per_thread_states);
3092
3093 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3094
3095 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3096 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3097
3098 eagerly_reclaim_humongous_regions();
3099
3100 record_obj_copy_mem_stats();
3101 _survivor_evac_stats.adjust_desired_plab_sz();
3102 _old_evac_stats.adjust_desired_plab_sz();
3103
3104 double start = os::elapsedTime();
3105 start_new_collection_set();
3106 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3107
3108 if (evacuation_failed()) {
3109 set_used(recalculate_used());
3110 if (_archive_allocator != NULL) {
3111 _archive_allocator->clear_used();
3112 }
3113 for (uint i = 0; i < ParallelGCThreads; i++) {
3114 if (_evacuation_failed_info_array[i].has_failed()) {
3115 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3116 }
3117 }
3118 } else {
3119 // The "used" of the the collection set have already been subtracted
3120 // when they were freed. Add in the bytes evacuated.
3121 increase_used(g1_policy()->bytes_copied_during_gc());
3122 }
3123
3124 if (collector_state()->during_initial_mark_pause()) {
3125 // We have to do this before we notify the CM threads that
3126 // they can start working to make sure that all the
3127 // appropriate initialization is done on the CM object.
3128 concurrent_mark()->checkpoint_roots_initial_post();
3129 collector_state()->set_mark_in_progress(true);
3130 // Note that we don't actually trigger the CM thread at
3131 // this point. We do that later when we're sure that
3132 // the current thread has completed its logging output.
3133 }
3134
3135 allocate_dummy_regions();
3136
3137 _allocator->init_mutator_alloc_region();
3138
3139 {
3140 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3141 if (expand_bytes > 0) {
3142 size_t bytes_before = capacity();
3143 // No need for an ergo logging here,
3144 // expansion_amount() does this when it returns a value > 0.
3145 double expand_ms;
3146 if (!expand(expand_bytes, _workers, &expand_ms)) {
3147 // We failed to expand the heap. Cannot do anything about it.
3148 }
3149 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3150 }
3151 }
3152
3153 // We redo the verification but now wrt to the new CSet which
3154 // has just got initialized after the previous CSet was freed.
3155 _cm->verify_no_cset_oops();
3156
3157 // This timing is only used by the ergonomics to handle our pause target.
3158 // It is unclear why this should not include the full pause. We will
3159 // investigate this in CR 7178365.
3160 double sample_end_time_sec = os::elapsedTime();
3161 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3162 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3163 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3164
3165 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3166 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3167
3168 if (VerifyRememberedSets) {
3169 log_info(gc, verify)("[Verifying RemSets after GC]");
3170 VerifyRegionRemSetClosure v_cl;
3171 heap_region_iterate(&v_cl);
3172 }
3173
3174 _verifier->verify_after_gc();
3175 _verifier->check_bitmaps("GC End");
3176
3177 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3178 ref_processor_stw()->verify_no_references_recorded();
3179
3180 // CM reference discovery will be re-enabled if necessary.
3181 }
3182
3183 #ifdef TRACESPINNING
3184 ParallelTaskTerminator::print_termination_counts();
3185 #endif
3186
3187 gc_epilogue(false);
3188 }
3189
3190 // Print the remainder of the GC log output.
3191 if (evacuation_failed()) {
3192 log_info(gc)("To-space exhausted");
3193 }
3194
3195 g1_policy()->print_phases();
3196 heap_transition.print();
3197
3198 // It is not yet to safe to tell the concurrent mark to
3199 // start as we have some optional output below. We don't want the
3200 // output from the concurrent mark thread interfering with this
3201 // logging output either.
3202
3203 _hrm.verify_optional();
3204 _verifier->verify_region_sets_optional();
3205
3206 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3207 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3208
3209 print_heap_after_gc();
3210 print_heap_regions();
3211 trace_heap_after_gc(_gc_tracer_stw);
3212
3213 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3214 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3215 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3216 // before any GC notifications are raised.
3217 g1mm()->update_sizes();
3218
3219 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3220 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3221 _gc_timer_stw->register_gc_end();
3222 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3223 }
3224 // It should now be safe to tell the concurrent mark thread to start
3225 // without its logging output interfering with the logging output
3226 // that came from the pause.
3227
3228 if (should_start_conc_mark) {
3229 // CAUTION: after the doConcurrentMark() call below,
3230 // the concurrent marking thread(s) could be running
3231 // concurrently with us. Make sure that anything after
3232 // this point does not assume that we are the only GC thread
3233 // running. Note: of course, the actual marking work will
3234 // not start until the safepoint itself is released in
3235 // SuspendibleThreadSet::desynchronize().
3236 doConcurrentMark();
3237 }
3238
3239 return true;
3240 }
3241
3242 void G1CollectedHeap::remove_self_forwarding_pointers() {
3243 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3244 workers()->run_task(&rsfp_task);
3245 }
3246
3247 void G1CollectedHeap::restore_after_evac_failure() {
3248 double remove_self_forwards_start = os::elapsedTime();
3249
3250 remove_self_forwarding_pointers();
3251 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3252 _preserved_marks_set.restore(&task_executor);
3253
3254 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3255 }
3256
3257 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3258 if (!_evacuation_failed) {
3259 _evacuation_failed = true;
3260 }
3261
3262 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3263 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3264 }
3265
3266 bool G1ParEvacuateFollowersClosure::offer_termination() {
3267 G1ParScanThreadState* const pss = par_scan_state();
3268 start_term_time();
3269 const bool res = terminator()->offer_termination();
3270 end_term_time();
3271 return res;
3272 }
3273
3274 void G1ParEvacuateFollowersClosure::do_void() {
3275 G1ParScanThreadState* const pss = par_scan_state();
3276 pss->trim_queue();
3277 do {
3278 pss->steal_and_trim_queue(queues());
3279 } while (!offer_termination());
3280 }
3281
3282 class G1ParTask : public AbstractGangTask {
3283 protected:
3284 G1CollectedHeap* _g1h;
3285 G1ParScanThreadStateSet* _pss;
3286 RefToScanQueueSet* _queues;
3287 G1RootProcessor* _root_processor;
3288 ParallelTaskTerminator _terminator;
3289 uint _n_workers;
3290
3291 public:
3292 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3293 : AbstractGangTask("G1 collection"),
3294 _g1h(g1h),
3295 _pss(per_thread_states),
3296 _queues(task_queues),
3297 _root_processor(root_processor),
3298 _terminator(n_workers, _queues),
3299 _n_workers(n_workers)
3300 {}
3301
3302 void work(uint worker_id) {
3303 if (worker_id >= _n_workers) return; // no work needed this round
3304
3305 double start_sec = os::elapsedTime();
3306 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3307
3308 {
3309 ResourceMark rm;
3310 HandleMark hm;
3311
3312 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3313
3314 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3315 pss->set_ref_processor(rp);
3316
3317 double start_strong_roots_sec = os::elapsedTime();
3318
3319 _root_processor->evacuate_roots(pss->closures(), worker_id);
3320
3321 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3322 // treating the nmethods visited to act as roots for concurrent marking.
3323 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3324 // objects copied by the current evacuation.
3325 _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3326 pss->closures()->weak_codeblobs(),
3327 worker_id);
3328
3329 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3330
3331 double term_sec = 0.0;
3332 size_t evac_term_attempts = 0;
3333 {
3334 double start = os::elapsedTime();
3335 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3336 evac.do_void();
3337
3338 evac_term_attempts = evac.term_attempts();
3339 term_sec = evac.term_time();
3340 double elapsed_sec = os::elapsedTime() - start;
3341 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3342 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3343 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3344 }
3345
3346 assert(pss->queue_is_empty(), "should be empty");
3347
3348 if (log_is_enabled(Debug, gc, task, stats)) {
3349 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3350 size_t lab_waste;
3351 size_t lab_undo_waste;
3352 pss->waste(lab_waste, lab_undo_waste);
3353 _g1h->print_termination_stats(worker_id,
3354 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3355 strong_roots_sec * 1000.0, /* strong roots time */
3356 term_sec * 1000.0, /* evac term time */
3357 evac_term_attempts, /* evac term attempts */
3358 lab_waste, /* alloc buffer waste */
3359 lab_undo_waste /* undo waste */
3360 );
3361 }
3362
3363 // Close the inner scope so that the ResourceMark and HandleMark
3364 // destructors are executed here and are included as part of the
3365 // "GC Worker Time".
3366 }
3367 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3368 }
3369 };
3370
3371 void G1CollectedHeap::print_termination_stats_hdr() {
3372 log_debug(gc, task, stats)("GC Termination Stats");
3373 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3374 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3375 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3376 }
3377
3378 void G1CollectedHeap::print_termination_stats(uint worker_id,
3379 double elapsed_ms,
3380 double strong_roots_ms,
3381 double term_ms,
3382 size_t term_attempts,
3383 size_t alloc_buffer_waste,
3384 size_t undo_waste) const {
3385 log_debug(gc, task, stats)
3386 ("%3d %9.2f %9.2f %6.2f "
3387 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3388 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3389 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3390 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3391 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3392 alloc_buffer_waste * HeapWordSize / K,
3393 undo_waste * HeapWordSize / K);
3394 }
3395
3396 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3397 private:
3398 BoolObjectClosure* _is_alive;
3399 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3400
3401 int _initial_string_table_size;
3402 int _initial_symbol_table_size;
3403
3404 bool _process_strings;
3405 int _strings_processed;
3406 int _strings_removed;
3407
3408 bool _process_symbols;
3409 int _symbols_processed;
3410 int _symbols_removed;
3411
3412 bool _process_string_dedup;
3413
3414 public:
3415 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3416 AbstractGangTask("String/Symbol Unlinking"),
3417 _is_alive(is_alive),
3418 _dedup_closure(is_alive, NULL, false),
3419 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3420 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3421 _process_string_dedup(process_string_dedup) {
3422
3423 _initial_string_table_size = StringTable::the_table()->table_size();
3424 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3425 if (process_strings) {
3426 StringTable::clear_parallel_claimed_index();
3427 }
3428 if (process_symbols) {
3429 SymbolTable::clear_parallel_claimed_index();
3430 }
3431 }
3432
3433 ~G1StringAndSymbolCleaningTask() {
3434 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3435 "claim value %d after unlink less than initial string table size %d",
3436 StringTable::parallel_claimed_index(), _initial_string_table_size);
3437 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3438 "claim value %d after unlink less than initial symbol table size %d",
3439 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3440
3441 log_info(gc, stringtable)(
3442 "Cleaned string and symbol table, "
3443 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3444 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3445 strings_processed(), strings_removed(),
3446 symbols_processed(), symbols_removed());
3447 }
3448
3449 void work(uint worker_id) {
3450 int strings_processed = 0;
3451 int strings_removed = 0;
3452 int symbols_processed = 0;
3453 int symbols_removed = 0;
3454 if (_process_strings) {
3455 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3456 Atomic::add(strings_processed, &_strings_processed);
3457 Atomic::add(strings_removed, &_strings_removed);
3458 }
3459 if (_process_symbols) {
3460 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3461 Atomic::add(symbols_processed, &_symbols_processed);
3462 Atomic::add(symbols_removed, &_symbols_removed);
3463 }
3464 if (_process_string_dedup) {
3465 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3466 }
3467 }
3468
3469 size_t strings_processed() const { return (size_t)_strings_processed; }
3470 size_t strings_removed() const { return (size_t)_strings_removed; }
3471
3472 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3473 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3474 };
3475
3476 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3477 private:
3478 static Monitor* _lock;
3479
3480 BoolObjectClosure* const _is_alive;
3481 const bool _unloading_occurred;
3482 const uint _num_workers;
3483
3484 // Variables used to claim nmethods.
3485 CompiledMethod* _first_nmethod;
3486 CompiledMethod* volatile _claimed_nmethod;
3487
3488 // The list of nmethods that need to be processed by the second pass.
3489 CompiledMethod* volatile _postponed_list;
3490 volatile uint _num_entered_barrier;
3491
3492 public:
3493 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3494 _is_alive(is_alive),
3495 _unloading_occurred(unloading_occurred),
3496 _num_workers(num_workers),
3497 _first_nmethod(NULL),
3498 _claimed_nmethod(NULL),
3499 _postponed_list(NULL),
3500 _num_entered_barrier(0)
3501 {
3502 CompiledMethod::increase_unloading_clock();
3503 // Get first alive nmethod
3504 CompiledMethodIterator iter = CompiledMethodIterator();
3505 if(iter.next_alive()) {
3506 _first_nmethod = iter.method();
3507 }
3508 _claimed_nmethod = _first_nmethod;
3509 }
3510
3511 ~G1CodeCacheUnloadingTask() {
3512 CodeCache::verify_clean_inline_caches();
3513
3514 CodeCache::set_needs_cache_clean(false);
3515 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3516
3517 CodeCache::verify_icholder_relocations();
3518 }
3519
3520 private:
3521 void add_to_postponed_list(CompiledMethod* nm) {
3522 CompiledMethod* old;
3523 do {
3524 old = _postponed_list;
3525 nm->set_unloading_next(old);
3526 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3527 }
3528
3529 void clean_nmethod(CompiledMethod* nm) {
3530 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3531
3532 if (postponed) {
3533 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3534 add_to_postponed_list(nm);
3535 }
3536
3537 // Mark that this thread has been cleaned/unloaded.
3538 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3539 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3540 }
3541
3542 void clean_nmethod_postponed(CompiledMethod* nm) {
3543 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3544 }
3545
3546 static const int MaxClaimNmethods = 16;
3547
3548 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3549 CompiledMethod* first;
3550 CompiledMethodIterator last;
3551
3552 do {
3553 *num_claimed_nmethods = 0;
3554
3555 first = _claimed_nmethod;
3556 last = CompiledMethodIterator(first);
3557
3558 if (first != NULL) {
3559
3560 for (int i = 0; i < MaxClaimNmethods; i++) {
3561 if (!last.next_alive()) {
3562 break;
3563 }
3564 claimed_nmethods[i] = last.method();
3565 (*num_claimed_nmethods)++;
3566 }
3567 }
3568
3569 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3570 }
3571
3572 CompiledMethod* claim_postponed_nmethod() {
3573 CompiledMethod* claim;
3574 CompiledMethod* next;
3575
3576 do {
3577 claim = _postponed_list;
3578 if (claim == NULL) {
3579 return NULL;
3580 }
3581
3582 next = claim->unloading_next();
3583
3584 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3585
3586 return claim;
3587 }
3588
3589 public:
3590 // Mark that we're done with the first pass of nmethod cleaning.
3591 void barrier_mark(uint worker_id) {
3592 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3593 _num_entered_barrier++;
3594 if (_num_entered_barrier == _num_workers) {
3595 ml.notify_all();
3596 }
3597 }
3598
3599 // See if we have to wait for the other workers to
3600 // finish their first-pass nmethod cleaning work.
3601 void barrier_wait(uint worker_id) {
3602 if (_num_entered_barrier < _num_workers) {
3603 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3604 while (_num_entered_barrier < _num_workers) {
3605 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3606 }
3607 }
3608 }
3609
3610 // Cleaning and unloading of nmethods. Some work has to be postponed
3611 // to the second pass, when we know which nmethods survive.
3612 void work_first_pass(uint worker_id) {
3613 // The first nmethods is claimed by the first worker.
3614 if (worker_id == 0 && _first_nmethod != NULL) {
3615 clean_nmethod(_first_nmethod);
3616 _first_nmethod = NULL;
3617 }
3618
3619 int num_claimed_nmethods;
3620 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3621
3622 while (true) {
3623 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3624
3625 if (num_claimed_nmethods == 0) {
3626 break;
3627 }
3628
3629 for (int i = 0; i < num_claimed_nmethods; i++) {
3630 clean_nmethod(claimed_nmethods[i]);
3631 }
3632 }
3633 }
3634
3635 void work_second_pass(uint worker_id) {
3636 CompiledMethod* nm;
3637 // Take care of postponed nmethods.
3638 while ((nm = claim_postponed_nmethod()) != NULL) {
3639 clean_nmethod_postponed(nm);
3640 }
3641 }
3642 };
3643
3644 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3645
3646 class G1KlassCleaningTask : public StackObj {
3647 BoolObjectClosure* _is_alive;
3648 volatile int _clean_klass_tree_claimed;
3649 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3650
3651 public:
3652 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3653 _is_alive(is_alive),
3654 _clean_klass_tree_claimed(0),
3655 _klass_iterator() {
3656 }
3657
3658 private:
3659 bool claim_clean_klass_tree_task() {
3660 if (_clean_klass_tree_claimed) {
3661 return false;
3662 }
3663
3664 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3665 }
3666
3667 InstanceKlass* claim_next_klass() {
3668 Klass* klass;
3669 do {
3670 klass =_klass_iterator.next_klass();
3671 } while (klass != NULL && !klass->is_instance_klass());
3672
3673 // this can be null so don't call InstanceKlass::cast
3674 return static_cast<InstanceKlass*>(klass);
3675 }
3676
3677 public:
3678
3679 void clean_klass(InstanceKlass* ik) {
3680 ik->clean_weak_instanceklass_links(_is_alive);
3681 }
3682
3683 void work() {
3684 ResourceMark rm;
3685
3686 // One worker will clean the subklass/sibling klass tree.
3687 if (claim_clean_klass_tree_task()) {
3688 Klass::clean_subklass_tree(_is_alive);
3689 }
3690
3691 // All workers will help cleaning the classes,
3692 InstanceKlass* klass;
3693 while ((klass = claim_next_klass()) != NULL) {
3694 clean_klass(klass);
3695 }
3696 }
3697 };
3698
3699 class G1ResolvedMethodCleaningTask : public StackObj {
3700 BoolObjectClosure* _is_alive;
3701 volatile int _resolved_method_task_claimed;
3702 public:
3703 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3704 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3705
3706 bool claim_resolved_method_task() {
3707 if (_resolved_method_task_claimed) {
3708 return false;
3709 }
3710 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3711 }
3712
3713 // These aren't big, one thread can do it all.
3714 void work() {
3715 if (claim_resolved_method_task()) {
3716 ResolvedMethodTable::unlink(_is_alive);
3717 }
3718 }
3719 };
3720
3721
3722 // To minimize the remark pause times, the tasks below are done in parallel.
3723 class G1ParallelCleaningTask : public AbstractGangTask {
3724 private:
3725 G1StringAndSymbolCleaningTask _string_symbol_task;
3726 G1CodeCacheUnloadingTask _code_cache_task;
3727 G1KlassCleaningTask _klass_cleaning_task;
3728 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3729
3730 public:
3731 // The constructor is run in the VMThread.
3732 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3733 AbstractGangTask("Parallel Cleaning"),
3734 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3735 _code_cache_task(num_workers, is_alive, unloading_occurred),
3736 _klass_cleaning_task(is_alive),
3737 _resolved_method_cleaning_task(is_alive) {
3738 }
3739
3740 // The parallel work done by all worker threads.
3741 void work(uint worker_id) {
3742 // Do first pass of code cache cleaning.
3743 _code_cache_task.work_first_pass(worker_id);
3744
3745 // Let the threads mark that the first pass is done.
3746 _code_cache_task.barrier_mark(worker_id);
3747
3748 // Clean the Strings and Symbols.
3749 _string_symbol_task.work(worker_id);
3750
3751 // Clean unreferenced things in the ResolvedMethodTable
3752 _resolved_method_cleaning_task.work();
3753
3754 // Wait for all workers to finish the first code cache cleaning pass.
3755 _code_cache_task.barrier_wait(worker_id);
3756
3757 // Do the second code cache cleaning work, which realize on
3758 // the liveness information gathered during the first pass.
3759 _code_cache_task.work_second_pass(worker_id);
3760
3761 // Clean all klasses that were not unloaded.
3762 _klass_cleaning_task.work();
3763 }
3764 };
3765
3766
3767 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3768 bool class_unloading_occurred) {
3769 uint n_workers = workers()->active_workers();
3770
3771 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3772 workers()->run_task(&g1_unlink_task);
3773 }
3774
3775 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3776 bool process_strings,
3777 bool process_symbols,
3778 bool process_string_dedup) {
3779 if (!process_strings && !process_symbols && !process_string_dedup) {
3780 // Nothing to clean.
3781 return;
3782 }
3783
3784 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3785 workers()->run_task(&g1_unlink_task);
3786
3787 }
3788
3789 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3790 private:
3791 DirtyCardQueueSet* _queue;
3792 G1CollectedHeap* _g1h;
3793 public:
3794 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3795 _queue(queue), _g1h(g1h) { }
3796
3797 virtual void work(uint worker_id) {
3798 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3799 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3800
3801 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3802 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3803
3804 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3805 }
3806 };
3807
3808 void G1CollectedHeap::redirty_logged_cards() {
3809 double redirty_logged_cards_start = os::elapsedTime();
3810
3811 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3812 dirty_card_queue_set().reset_for_par_iteration();
3813 workers()->run_task(&redirty_task);
3814
3815 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3816 dcq.merge_bufferlists(&dirty_card_queue_set());
3817 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3818
3819 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3820 }
3821
3822 // Weak Reference Processing support
3823
3824 // An always "is_alive" closure that is used to preserve referents.
3825 // If the object is non-null then it's alive. Used in the preservation
3826 // of referent objects that are pointed to by reference objects
3827 // discovered by the CM ref processor.
3828 class G1AlwaysAliveClosure: public BoolObjectClosure {
3829 G1CollectedHeap* _g1;
3830 public:
3831 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3832 bool do_object_b(oop p) {
3833 if (p != NULL) {
3834 return true;
3835 }
3836 return false;
3837 }
3838 };
3839
3840 bool G1STWIsAliveClosure::do_object_b(oop p) {
3841 // An object is reachable if it is outside the collection set,
3842 // or is inside and copied.
3843 return !_g1->is_in_cset(p) || p->is_forwarded();
3844 }
3845
3846 // Non Copying Keep Alive closure
3847 class G1KeepAliveClosure: public OopClosure {
3848 G1CollectedHeap* _g1;
3849 public:
3850 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3851 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3852 void do_oop(oop* p) {
3853 oop obj = *p;
3854 assert(obj != NULL, "the caller should have filtered out NULL values");
3855
3856 const InCSetState cset_state = _g1->in_cset_state(obj);
3857 if (!cset_state.is_in_cset_or_humongous()) {
3858 return;
3859 }
3860 if (cset_state.is_in_cset()) {
3861 assert( obj->is_forwarded(), "invariant" );
3862 *p = obj->forwardee();
3863 } else {
3864 assert(!obj->is_forwarded(), "invariant" );
3865 assert(cset_state.is_humongous(),
3866 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3867 _g1->set_humongous_is_live(obj);
3868 }
3869 }
3870 };
3871
3872 // Copying Keep Alive closure - can be called from both
3873 // serial and parallel code as long as different worker
3874 // threads utilize different G1ParScanThreadState instances
3875 // and different queues.
3876
3877 class G1CopyingKeepAliveClosure: public OopClosure {
3878 G1CollectedHeap* _g1h;
3879 OopClosure* _copy_non_heap_obj_cl;
3880 G1ParScanThreadState* _par_scan_state;
3881
3882 public:
3883 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3884 OopClosure* non_heap_obj_cl,
3885 G1ParScanThreadState* pss):
3886 _g1h(g1h),
3887 _copy_non_heap_obj_cl(non_heap_obj_cl),
3888 _par_scan_state(pss)
3889 {}
3890
3891 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3892 virtual void do_oop( oop* p) { do_oop_work(p); }
3893
3894 template <class T> void do_oop_work(T* p) {
3895 oop obj = oopDesc::load_decode_heap_oop(p);
3896
3897 if (_g1h->is_in_cset_or_humongous(obj)) {
3898 // If the referent object has been forwarded (either copied
3899 // to a new location or to itself in the event of an
3900 // evacuation failure) then we need to update the reference
3901 // field and, if both reference and referent are in the G1
3902 // heap, update the RSet for the referent.
3903 //
3904 // If the referent has not been forwarded then we have to keep
3905 // it alive by policy. Therefore we have copy the referent.
3906 //
3907 // If the reference field is in the G1 heap then we can push
3908 // on the PSS queue. When the queue is drained (after each
3909 // phase of reference processing) the object and it's followers
3910 // will be copied, the reference field set to point to the
3911 // new location, and the RSet updated. Otherwise we need to
3912 // use the the non-heap or metadata closures directly to copy
3913 // the referent object and update the pointer, while avoiding
3914 // updating the RSet.
3915
3916 if (_g1h->is_in_g1_reserved(p)) {
3917 _par_scan_state->push_on_queue(p);
3918 } else {
3919 assert(!Metaspace::contains((const void*)p),
3920 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3921 _copy_non_heap_obj_cl->do_oop(p);
3922 }
3923 }
3924 }
3925 };
3926
3927 // Serial drain queue closure. Called as the 'complete_gc'
3928 // closure for each discovered list in some of the
3929 // reference processing phases.
3930
3931 class G1STWDrainQueueClosure: public VoidClosure {
3932 protected:
3933 G1CollectedHeap* _g1h;
3934 G1ParScanThreadState* _par_scan_state;
3935
3936 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3937
3938 public:
3939 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3940 _g1h(g1h),
3941 _par_scan_state(pss)
3942 { }
3943
3944 void do_void() {
3945 G1ParScanThreadState* const pss = par_scan_state();
3946 pss->trim_queue();
3947 }
3948 };
3949
3950 // Parallel Reference Processing closures
3951
3952 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3953 // processing during G1 evacuation pauses.
3954
3955 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3956 private:
3957 G1CollectedHeap* _g1h;
3958 G1ParScanThreadStateSet* _pss;
3959 RefToScanQueueSet* _queues;
3960 WorkGang* _workers;
3961 uint _active_workers;
3962
3963 public:
3964 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3965 G1ParScanThreadStateSet* per_thread_states,
3966 WorkGang* workers,
3967 RefToScanQueueSet *task_queues,
3968 uint n_workers) :
3969 _g1h(g1h),
3970 _pss(per_thread_states),
3971 _queues(task_queues),
3972 _workers(workers),
3973 _active_workers(n_workers)
3974 {
3975 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3976 }
3977
3978 // Executes the given task using concurrent marking worker threads.
3979 virtual void execute(ProcessTask& task);
3980 virtual void execute(EnqueueTask& task);
3981 };
3982
3983 // Gang task for possibly parallel reference processing
3984
3985 class G1STWRefProcTaskProxy: public AbstractGangTask {
3986 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3987 ProcessTask& _proc_task;
3988 G1CollectedHeap* _g1h;
3989 G1ParScanThreadStateSet* _pss;
3990 RefToScanQueueSet* _task_queues;
3991 ParallelTaskTerminator* _terminator;
3992
3993 public:
3994 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3995 G1CollectedHeap* g1h,
3996 G1ParScanThreadStateSet* per_thread_states,
3997 RefToScanQueueSet *task_queues,
3998 ParallelTaskTerminator* terminator) :
3999 AbstractGangTask("Process reference objects in parallel"),
4000 _proc_task(proc_task),
4001 _g1h(g1h),
4002 _pss(per_thread_states),
4003 _task_queues(task_queues),
4004 _terminator(terminator)
4005 {}
4006
4007 virtual void work(uint worker_id) {
4008 // The reference processing task executed by a single worker.
4009 ResourceMark rm;
4010 HandleMark hm;
4011
4012 G1STWIsAliveClosure is_alive(_g1h);
4013
4014 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4015 pss->set_ref_processor(NULL);
4016
4017 // Keep alive closure.
4018 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4019
4020 // Complete GC closure
4021 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4022
4023 // Call the reference processing task's work routine.
4024 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4025
4026 // Note we cannot assert that the refs array is empty here as not all
4027 // of the processing tasks (specifically phase2 - pp2_work) execute
4028 // the complete_gc closure (which ordinarily would drain the queue) so
4029 // the queue may not be empty.
4030 }
4031 };
4032
4033 // Driver routine for parallel reference processing.
4034 // Creates an instance of the ref processing gang
4035 // task and has the worker threads execute it.
4036 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4037 assert(_workers != NULL, "Need parallel worker threads.");
4038
4039 ParallelTaskTerminator terminator(_active_workers, _queues);
4040 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4041
4042 _workers->run_task(&proc_task_proxy);
4043 }
4044
4045 // Gang task for parallel reference enqueueing.
4046
4047 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4048 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4049 EnqueueTask& _enq_task;
4050
4051 public:
4052 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4053 AbstractGangTask("Enqueue reference objects in parallel"),
4054 _enq_task(enq_task)
4055 { }
4056
4057 virtual void work(uint worker_id) {
4058 _enq_task.work(worker_id);
4059 }
4060 };
4061
4062 // Driver routine for parallel reference enqueueing.
4063 // Creates an instance of the ref enqueueing gang
4064 // task and has the worker threads execute it.
4065
4066 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4067 assert(_workers != NULL, "Need parallel worker threads.");
4068
4069 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4070
4071 _workers->run_task(&enq_task_proxy);
4072 }
4073
4074 // End of weak reference support closures
4075
4076 // Abstract task used to preserve (i.e. copy) any referent objects
4077 // that are in the collection set and are pointed to by reference
4078 // objects discovered by the CM ref processor.
4079
4080 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4081 protected:
4082 G1CollectedHeap* _g1h;
4083 G1ParScanThreadStateSet* _pss;
4084 RefToScanQueueSet* _queues;
4085 ParallelTaskTerminator _terminator;
4086 uint _n_workers;
4087
4088 public:
4089 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4090 AbstractGangTask("ParPreserveCMReferents"),
4091 _g1h(g1h),
4092 _pss(per_thread_states),
4093 _queues(task_queues),
4094 _terminator(workers, _queues),
4095 _n_workers(workers)
4096 {
4097 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4098 }
4099
4100 void work(uint worker_id) {
4101 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4102
4103 ResourceMark rm;
4104 HandleMark hm;
4105
4106 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4107 pss->set_ref_processor(NULL);
4108 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4109
4110 // Is alive closure
4111 G1AlwaysAliveClosure always_alive(_g1h);
4112
4113 // Copying keep alive closure. Applied to referent objects that need
4114 // to be copied.
4115 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4116
4117 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4118
4119 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4120 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4121
4122 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4123 // So this must be true - but assert just in case someone decides to
4124 // change the worker ids.
4125 assert(worker_id < limit, "sanity");
4126 assert(!rp->discovery_is_atomic(), "check this code");
4127
4128 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4129 for (uint idx = worker_id; idx < limit; idx += stride) {
4130 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4131
4132 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4133 while (iter.has_next()) {
4134 // Since discovery is not atomic for the CM ref processor, we
4135 // can see some null referent objects.
4136 iter.load_ptrs(DEBUG_ONLY(true));
4137 oop ref = iter.obj();
4138
4139 // This will filter nulls.
4140 if (iter.is_referent_alive()) {
4141 iter.make_referent_alive();
4142 }
4143 iter.move_to_next();
4144 }
4145 }
4146
4147 // Drain the queue - which may cause stealing
4148 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4149 drain_queue.do_void();
4150 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4151 assert(pss->queue_is_empty(), "should be");
4152 }
4153 };
4154
4155 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4156 // Any reference objects, in the collection set, that were 'discovered'
4157 // by the CM ref processor should have already been copied (either by
4158 // applying the external root copy closure to the discovered lists, or
4159 // by following an RSet entry).
4160 //
4161 // But some of the referents, that are in the collection set, that these
4162 // reference objects point to may not have been copied: the STW ref
4163 // processor would have seen that the reference object had already
4164 // been 'discovered' and would have skipped discovering the reference,
4165 // but would not have treated the reference object as a regular oop.
4166 // As a result the copy closure would not have been applied to the
4167 // referent object.
4168 //
4169 // We need to explicitly copy these referent objects - the references
4170 // will be processed at the end of remarking.
4171 //
4172 // We also need to do this copying before we process the reference
4173 // objects discovered by the STW ref processor in case one of these
4174 // referents points to another object which is also referenced by an
4175 // object discovered by the STW ref processor.
4176 double preserve_cm_referents_time = 0.0;
4177
4178 // To avoid spawning task when there is no work to do, check that
4179 // a concurrent cycle is active and that some references have been
4180 // discovered.
4181 if (concurrent_mark()->cm_thread()->during_cycle() &&
4182 ref_processor_cm()->has_discovered_references()) {
4183 double preserve_cm_referents_start = os::elapsedTime();
4184 uint no_of_gc_workers = workers()->active_workers();
4185 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4186 per_thread_states,
4187 no_of_gc_workers,
4188 _task_queues);
4189 workers()->run_task(&keep_cm_referents);
4190 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4191 }
4192
4193 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4194 }
4195
4196 // Weak Reference processing during an evacuation pause (part 1).
4197 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4198 double ref_proc_start = os::elapsedTime();
4199
4200 ReferenceProcessor* rp = _ref_processor_stw;
4201 assert(rp->discovery_enabled(), "should have been enabled");
4202
4203 // Closure to test whether a referent is alive.
4204 G1STWIsAliveClosure is_alive(this);
4205
4206 // Even when parallel reference processing is enabled, the processing
4207 // of JNI refs is serial and performed serially by the current thread
4208 // rather than by a worker. The following PSS will be used for processing
4209 // JNI refs.
4210
4211 // Use only a single queue for this PSS.
4212 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4213 pss->set_ref_processor(NULL);
4214 assert(pss->queue_is_empty(), "pre-condition");
4215
4216 // Keep alive closure.
4217 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4218
4219 // Serial Complete GC closure
4220 G1STWDrainQueueClosure drain_queue(this, pss);
4221
4222 // Setup the soft refs policy...
4223 rp->setup_policy(false);
4224
4225 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4226
4227 ReferenceProcessorStats stats;
4228 if (!rp->processing_is_mt()) {
4229 // Serial reference processing...
4230 stats = rp->process_discovered_references(&is_alive,
4231 &keep_alive,
4232 &drain_queue,
4233 NULL,
4234 pt);
4235 } else {
4236 uint no_of_gc_workers = workers()->active_workers();
4237
4238 // Parallel reference processing
4239 assert(no_of_gc_workers <= rp->max_num_q(),
4240 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4241 no_of_gc_workers, rp->max_num_q());
4242
4243 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4244 stats = rp->process_discovered_references(&is_alive,
4245 &keep_alive,
4246 &drain_queue,
4247 &par_task_executor,
4248 pt);
4249 }
4250
4251 _gc_tracer_stw->report_gc_reference_stats(stats);
4252
4253 // We have completed copying any necessary live referent objects.
4254 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4255
4256 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4257 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4258 }
4259
4260 // Weak Reference processing during an evacuation pause (part 2).
4261 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4262 double ref_enq_start = os::elapsedTime();
4263
4264 ReferenceProcessor* rp = _ref_processor_stw;
4265 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4266
4267 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4268
4269 // Now enqueue any remaining on the discovered lists on to
4270 // the pending list.
4271 if (!rp->processing_is_mt()) {
4272 // Serial reference processing...
4273 rp->enqueue_discovered_references(NULL, pt);
4274 } else {
4275 // Parallel reference enqueueing
4276
4277 uint n_workers = workers()->active_workers();
4278
4279 assert(n_workers <= rp->max_num_q(),
4280 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4281 n_workers, rp->max_num_q());
4282
4283 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4284 rp->enqueue_discovered_references(&par_task_executor, pt);
4285 }
4286
4287 rp->verify_no_references_recorded();
4288 assert(!rp->discovery_enabled(), "should have been disabled");
4289
4290 // If during an initial mark pause we install a pending list head which is not otherwise reachable
4291 // ensure that it is marked in the bitmap for concurrent marking to discover.
4292 if (collector_state()->during_initial_mark_pause()) {
4293 oop pll_head = Universe::reference_pending_list();
4294 if (pll_head != NULL) {
4295 _cm->mark_in_next_bitmap(pll_head);
4296 }
4297 }
4298
4299 // FIXME
4300 // CM's reference processing also cleans up the string and symbol tables.
4301 // Should we do that here also? We could, but it is a serial operation
4302 // and could significantly increase the pause time.
4303
4304 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4305 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4306 }
4307
4308 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4309 double merge_pss_time_start = os::elapsedTime();
4310 per_thread_states->flush();
4311 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4312 }
4313
4314 void G1CollectedHeap::pre_evacuate_collection_set() {
4315 _expand_heap_after_alloc_failure = true;
4316 _evacuation_failed = false;
4317
4318 // Disable the hot card cache.
4319 _hot_card_cache->reset_hot_cache_claimed_index();
4320 _hot_card_cache->set_use_cache(false);
4321
4322 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4323 _preserved_marks_set.assert_empty();
4324
4325 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4326
4327 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4328 if (collector_state()->during_initial_mark_pause()) {
4329 double start_clear_claimed_marks = os::elapsedTime();
4330
4331 ClassLoaderDataGraph::clear_claimed_marks();
4332
4333 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4334 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4335 }
4336 }
4337
4338 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4339 // Should G1EvacuationFailureALot be in effect for this GC?
4340 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4341
4342 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4343
4344 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4345
4346 double start_par_time_sec = os::elapsedTime();
4347 double end_par_time_sec;
4348
4349 {
4350 const uint n_workers = workers()->active_workers();
4351 G1RootProcessor root_processor(this, n_workers);
4352 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4353
4354 print_termination_stats_hdr();
4355
4356 workers()->run_task(&g1_par_task);
4357 end_par_time_sec = os::elapsedTime();
4358
4359 // Closing the inner scope will execute the destructor
4360 // for the G1RootProcessor object. We record the current
4361 // elapsed time before closing the scope so that time
4362 // taken for the destructor is NOT included in the
4363 // reported parallel time.
4364 }
4365
4366 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4367 phase_times->record_par_time(par_time_ms);
4368
4369 double code_root_fixup_time_ms =
4370 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4371 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4372 }
4373
4374 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4375 // Process any discovered reference objects - we have
4376 // to do this _before_ we retire the GC alloc regions
4377 // as we may have to copy some 'reachable' referent
4378 // objects (and their reachable sub-graphs) that were
4379 // not copied during the pause.
4380 if (g1_policy()->should_process_references()) {
4381 preserve_cm_referents(per_thread_states);
4382 process_discovered_references(per_thread_states);
4383 } else {
4384 ref_processor_stw()->verify_no_references_recorded();
4385 }
4386
4387 G1STWIsAliveClosure is_alive(this);
4388 G1KeepAliveClosure keep_alive(this);
4389
4390 {
4391 double start = os::elapsedTime();
4392
4393 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4394
4395 double time_ms = (os::elapsedTime() - start) * 1000.0;
4396 g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4397 }
4398
4399 if (G1StringDedup::is_enabled()) {
4400 double fixup_start = os::elapsedTime();
4401
4402 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4403
4404 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4405 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4406 }
4407
4408 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4409
4410 if (evacuation_failed()) {
4411 restore_after_evac_failure();
4412
4413 // Reset the G1EvacuationFailureALot counters and flags
4414 // Note: the values are reset only when an actual
4415 // evacuation failure occurs.
4416 NOT_PRODUCT(reset_evacuation_should_fail();)
4417 }
4418
4419 _preserved_marks_set.assert_empty();
4420
4421 // Enqueue any remaining references remaining on the STW
4422 // reference processor's discovered lists. We need to do
4423 // this after the card table is cleaned (and verified) as
4424 // the act of enqueueing entries on to the pending list
4425 // will log these updates (and dirty their associated
4426 // cards). We need these updates logged to update any
4427 // RSets.
4428 if (g1_policy()->should_process_references()) {
4429 enqueue_discovered_references(per_thread_states);
4430 } else {
4431 g1_policy()->phase_times()->record_ref_enq_time(0);
4432 }
4433
4434 _allocator->release_gc_alloc_regions(evacuation_info);
4435
4436 merge_per_thread_state_info(per_thread_states);
4437
4438 // Reset and re-enable the hot card cache.
4439 // Note the counts for the cards in the regions in the
4440 // collection set are reset when the collection set is freed.
4441 _hot_card_cache->reset_hot_cache();
4442 _hot_card_cache->set_use_cache(true);
4443
4444 purge_code_root_memory();
4445
4446 redirty_logged_cards();
4447 #if COMPILER2_OR_JVMCI
4448 double start = os::elapsedTime();
4449 DerivedPointerTable::update_pointers();
4450 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4451 #endif
4452 g1_policy()->print_age_table();
4453 }
4454
4455 void G1CollectedHeap::record_obj_copy_mem_stats() {
4456 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4457
4458 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4459 create_g1_evac_summary(&_old_evac_stats));
4460 }
4461
4462 void G1CollectedHeap::free_region(HeapRegion* hr,
4463 FreeRegionList* free_list,
4464 bool skip_remset,
4465 bool skip_hot_card_cache,
4466 bool locked) {
4467 assert(!hr->is_free(), "the region should not be free");
4468 assert(!hr->is_empty(), "the region should not be empty");
4469 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4470 assert(free_list != NULL, "pre-condition");
4471
4472 if (G1VerifyBitmaps) {
4473 MemRegion mr(hr->bottom(), hr->end());
4474 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4475 }
4476
4477 // Clear the card counts for this region.
4478 // Note: we only need to do this if the region is not young
4479 // (since we don't refine cards in young regions).
4480 if (!skip_hot_card_cache && !hr->is_young()) {
4481 _hot_card_cache->reset_card_counts(hr);
4482 }
4483 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4484 free_list->add_ordered(hr);
4485 }
4486
4487 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4488 FreeRegionList* free_list,
4489 bool skip_remset) {
4490 assert(hr->is_humongous(), "this is only for humongous regions");
4491 assert(free_list != NULL, "pre-condition");
4492 hr->clear_humongous();
4493 free_region(hr, free_list, skip_remset);
4494 }
4495
4496 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4497 const uint humongous_regions_removed) {
4498 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4499 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4500 _old_set.bulk_remove(old_regions_removed);
4501 _humongous_set.bulk_remove(humongous_regions_removed);
4502 }
4503
4504 }
4505
4506 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4507 assert(list != NULL, "list can't be null");
4508 if (!list->is_empty()) {
4509 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4510 _hrm.insert_list_into_free_list(list);
4511 }
4512 }
4513
4514 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4515 decrease_used(bytes);
4516 }
4517
4518 class G1ParScrubRemSetTask: public AbstractGangTask {
4519 protected:
4520 G1RemSet* _g1rs;
4521 HeapRegionClaimer _hrclaimer;
4522
4523 public:
4524 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4525 AbstractGangTask("G1 ScrubRS"),
4526 _g1rs(g1_rs),
4527 _hrclaimer(num_workers) {
4528 }
4529
4530 void work(uint worker_id) {
4531 _g1rs->scrub(worker_id, &_hrclaimer);
4532 }
4533 };
4534
4535 void G1CollectedHeap::scrub_rem_set() {
4536 uint num_workers = workers()->active_workers();
4537 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4538 workers()->run_task(&g1_par_scrub_rs_task);
4539 }
4540
4541 class G1FreeCollectionSetTask : public AbstractGangTask {
4542 private:
4543
4544 // Closure applied to all regions in the collection set to do work that needs to
4545 // be done serially in a single thread.
4546 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4547 private:
4548 EvacuationInfo* _evacuation_info;
4549 const size_t* _surviving_young_words;
4550
4551 // Bytes used in successfully evacuated regions before the evacuation.
4552 size_t _before_used_bytes;
4553 // Bytes used in unsucessfully evacuated regions before the evacuation
4554 size_t _after_used_bytes;
4555
4556 size_t _bytes_allocated_in_old_since_last_gc;
4557
4558 size_t _failure_used_words;
4559 size_t _failure_waste_words;
4560
4561 FreeRegionList _local_free_list;
4562 public:
4563 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4564 HeapRegionClosure(),
4565 _evacuation_info(evacuation_info),
4566 _surviving_young_words(surviving_young_words),
4567 _before_used_bytes(0),
4568 _after_used_bytes(0),
4569 _bytes_allocated_in_old_since_last_gc(0),
4570 _failure_used_words(0),
4571 _failure_waste_words(0),
4572 _local_free_list("Local Region List for CSet Freeing") {
4573 }
4574
4575 virtual bool doHeapRegion(HeapRegion* r) {
4576 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4577
4578 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4579 g1h->clear_in_cset(r);
4580
4581 if (r->is_young()) {
4582 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4583 "Young index %d is wrong for region %u of type %s with %u young regions",
4584 r->young_index_in_cset(),
4585 r->hrm_index(),
4586 r->get_type_str(),
4587 g1h->collection_set()->young_region_length());
4588 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4589 r->record_surv_words_in_group(words_survived);
4590 }
4591
4592 if (!r->evacuation_failed()) {
4593 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4594 _before_used_bytes += r->used();
4595 g1h->free_region(r,
4596 &_local_free_list,
4597 true, /* skip_remset */
4598 true, /* skip_hot_card_cache */
4599 true /* locked */);
4600 } else {
4601 r->uninstall_surv_rate_group();
4602 r->set_young_index_in_cset(-1);
4603 r->set_evacuation_failed(false);
4604 // When moving a young gen region to old gen, we "allocate" that whole region
4605 // there. This is in addition to any already evacuated objects. Notify the
4606 // policy about that.
4607 // Old gen regions do not cause an additional allocation: both the objects
4608 // still in the region and the ones already moved are accounted for elsewhere.
4609 if (r->is_young()) {
4610 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4611 }
4612 // The region is now considered to be old.
4613 r->set_old();
4614 // Do some allocation statistics accounting. Regions that failed evacuation
4615 // are always made old, so there is no need to update anything in the young
4616 // gen statistics, but we need to update old gen statistics.
4617 size_t used_words = r->marked_bytes() / HeapWordSize;
4618
4619 _failure_used_words += used_words;
4620 _failure_waste_words += HeapRegion::GrainWords - used_words;
4621
4622 g1h->old_set_add(r);
4623 _after_used_bytes += r->used();
4624 }
4625 return false;
4626 }
4627
4628 void complete_work() {
4629 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4630
4631 _evacuation_info->set_regions_freed(_local_free_list.length());
4632 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4633
4634 g1h->prepend_to_freelist(&_local_free_list);
4635 g1h->decrement_summary_bytes(_before_used_bytes);
4636
4637 G1Policy* policy = g1h->g1_policy();
4638 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4639
4640 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4641 }
4642 };
4643
4644 G1CollectionSet* _collection_set;
4645 G1SerialFreeCollectionSetClosure _cl;
4646 const size_t* _surviving_young_words;
4647
4648 size_t _rs_lengths;
4649
4650 volatile jint _serial_work_claim;
4651
4652 struct WorkItem {
4653 uint region_idx;
4654 bool is_young;
4655 bool evacuation_failed;
4656
4657 WorkItem(HeapRegion* r) {
4658 region_idx = r->hrm_index();
4659 is_young = r->is_young();
4660 evacuation_failed = r->evacuation_failed();
4661 }
4662 };
4663
4664 volatile size_t _parallel_work_claim;
4665 size_t _num_work_items;
4666 WorkItem* _work_items;
4667
4668 void do_serial_work() {
4669 // Need to grab the lock to be allowed to modify the old region list.
4670 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4671 _collection_set->iterate(&_cl);
4672 }
4673
4674 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4675 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4676
4677 HeapRegion* r = g1h->region_at(region_idx);
4678 assert(!g1h->is_on_master_free_list(r), "sanity");
4679
4680 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4681
4682 if (!is_young) {
4683 g1h->_hot_card_cache->reset_card_counts(r);
4684 }
4685
4686 if (!evacuation_failed) {
4687 r->rem_set()->clear_locked();
4688 }
4689 }
4690
4691 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4692 private:
4693 size_t _cur_idx;
4694 WorkItem* _work_items;
4695 public:
4696 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4697
4698 virtual bool doHeapRegion(HeapRegion* r) {
4699 _work_items[_cur_idx++] = WorkItem(r);
4700 return false;
4701 }
4702 };
4703
4704 void prepare_work() {
4705 G1PrepareFreeCollectionSetClosure cl(_work_items);
4706 _collection_set->iterate(&cl);
4707 }
4708
4709 void complete_work() {
4710 _cl.complete_work();
4711
4712 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4713 policy->record_max_rs_lengths(_rs_lengths);
4714 policy->cset_regions_freed();
4715 }
4716 public:
4717 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4718 AbstractGangTask("G1 Free Collection Set"),
4719 _cl(evacuation_info, surviving_young_words),
4720 _collection_set(collection_set),
4721 _surviving_young_words(surviving_young_words),
4722 _serial_work_claim(0),
4723 _rs_lengths(0),
4724 _parallel_work_claim(0),
4725 _num_work_items(collection_set->region_length()),
4726 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4727 prepare_work();
4728 }
4729
4730 ~G1FreeCollectionSetTask() {
4731 complete_work();
4732 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4733 }
4734
4735 // Chunk size for work distribution. The chosen value has been determined experimentally
4736 // to be a good tradeoff between overhead and achievable parallelism.
4737 static uint chunk_size() { return 32; }
4738
4739 virtual void work(uint worker_id) {
4740 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4741
4742 // Claim serial work.
4743 if (_serial_work_claim == 0) {
4744 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4745 if (value == 0) {
4746 double serial_time = os::elapsedTime();
4747 do_serial_work();
4748 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4749 }
4750 }
4751
4752 // Start parallel work.
4753 double young_time = 0.0;
4754 bool has_young_time = false;
4755 double non_young_time = 0.0;
4756 bool has_non_young_time = false;
4757
4758 while (true) {
4759 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4760 size_t cur = end - chunk_size();
4761
4762 if (cur >= _num_work_items) {
4763 break;
4764 }
4765
4766 double start_time = os::elapsedTime();
4767
4768 end = MIN2(end, _num_work_items);
4769
4770 for (; cur < end; cur++) {
4771 bool is_young = _work_items[cur].is_young;
4772
4773 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4774
4775 double end_time = os::elapsedTime();
4776 double time_taken = end_time - start_time;
4777 if (is_young) {
4778 young_time += time_taken;
4779 has_young_time = true;
4780 } else {
4781 non_young_time += time_taken;
4782 has_non_young_time = true;
4783 }
4784 start_time = end_time;
4785 }
4786 }
4787
4788 if (has_young_time) {
4789 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4790 }
4791 if (has_non_young_time) {
4792 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4793 }
4794 }
4795 };
4796
4797 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4798 _eden.clear();
4799
4800 double free_cset_start_time = os::elapsedTime();
4801
4802 {
4803 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4804 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4805
4806 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4807
4808 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4809 cl.name(),
4810 num_workers,
4811 _collection_set.region_length());
4812 workers()->run_task(&cl, num_workers);
4813 }
4814 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4815
4816 collection_set->clear();
4817 }
4818
4819 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4820 private:
4821 FreeRegionList* _free_region_list;
4822 HeapRegionSet* _proxy_set;
4823 uint _humongous_objects_reclaimed;
4824 uint _humongous_regions_reclaimed;
4825 size_t _freed_bytes;
4826 public:
4827
4828 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4829 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4830 }
4831
4832 virtual bool doHeapRegion(HeapRegion* r) {
4833 if (!r->is_starts_humongous()) {
4834 return false;
4835 }
4836
4837 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4838
4839 oop obj = (oop)r->bottom();
4840 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4841
4842 // The following checks whether the humongous object is live are sufficient.
4843 // The main additional check (in addition to having a reference from the roots
4844 // or the young gen) is whether the humongous object has a remembered set entry.
4845 //
4846 // A humongous object cannot be live if there is no remembered set for it
4847 // because:
4848 // - there can be no references from within humongous starts regions referencing
4849 // the object because we never allocate other objects into them.
4850 // (I.e. there are no intra-region references that may be missed by the
4851 // remembered set)
4852 // - as soon there is a remembered set entry to the humongous starts region
4853 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4854 // until the end of a concurrent mark.
4855 //
4856 // It is not required to check whether the object has been found dead by marking
4857 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4858 // all objects allocated during that time are considered live.
4859 // SATB marking is even more conservative than the remembered set.
4860 // So if at this point in the collection there is no remembered set entry,
4861 // nobody has a reference to it.
4862 // At the start of collection we flush all refinement logs, and remembered sets
4863 // are completely up-to-date wrt to references to the humongous object.
4864 //
4865 // Other implementation considerations:
4866 // - never consider object arrays at this time because they would pose
4867 // considerable effort for cleaning up the the remembered sets. This is
4868 // required because stale remembered sets might reference locations that
4869 // are currently allocated into.
4870 uint region_idx = r->hrm_index();
4871 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4872 !r->rem_set()->is_empty()) {
4873 log_debug(gc, humongous)("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
4874 region_idx,
4875 (size_t)obj->size() * HeapWordSize,
4876 p2i(r->bottom()),
4877 r->rem_set()->occupied(),
4878 r->rem_set()->strong_code_roots_list_length(),
4879 next_bitmap->is_marked(r->bottom()),
4880 g1h->is_humongous_reclaim_candidate(region_idx),
4881 obj->is_typeArray()
4882 );
4883 return false;
4884 }
4885
4886 guarantee(obj->is_typeArray(),
4887 "Only eagerly reclaiming type arrays is supported, but the object "
4888 PTR_FORMAT " is not.", p2i(r->bottom()));
4889
4890 log_debug(gc, humongous)("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
4891 region_idx,
4892 (size_t)obj->size() * HeapWordSize,
4893 p2i(r->bottom()),
4894 r->rem_set()->occupied(),
4895 r->rem_set()->strong_code_roots_list_length(),
4896 next_bitmap->is_marked(r->bottom()),
4897 g1h->is_humongous_reclaim_candidate(region_idx),
4898 obj->is_typeArray()
4899 );
4900
4901 // Need to clear mark bit of the humongous object if already set.
4902 if (next_bitmap->is_marked(r->bottom())) {
4903 next_bitmap->clear(r->bottom());
4904 }
4905 _humongous_objects_reclaimed++;
4906 do {
4907 HeapRegion* next = g1h->next_region_in_humongous(r);
4908 _freed_bytes += r->used();
4909 r->set_containing_set(NULL);
4910 _humongous_regions_reclaimed++;
4911 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4912 r = next;
4913 } while (r != NULL);
4914
4915 return false;
4916 }
4917
4918 uint humongous_objects_reclaimed() {
4919 return _humongous_objects_reclaimed;
4920 }
4921
4922 uint humongous_regions_reclaimed() {
4923 return _humongous_regions_reclaimed;
4924 }
4925
4926 size_t bytes_freed() const {
4927 return _freed_bytes;
4928 }
4929 };
4930
4931 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4932 assert_at_safepoint(true);
4933
4934 if (!G1EagerReclaimHumongousObjects ||
4935 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4936 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4937 return;
4938 }
4939
4940 double start_time = os::elapsedTime();
4941
4942 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4943
4944 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4945 heap_region_iterate(&cl);
4946
4947 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4948
4949 G1HRPrinter* hrp = hr_printer();
4950 if (hrp->is_active()) {
4951 FreeRegionListIterator iter(&local_cleanup_list);
4952 while (iter.more_available()) {
4953 HeapRegion* hr = iter.get_next();
4954 hrp->cleanup(hr);
4955 }
4956 }
4957
4958 prepend_to_freelist(&local_cleanup_list);
4959 decrement_summary_bytes(cl.bytes_freed());
4960
4961 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4962 cl.humongous_objects_reclaimed());
4963 }
4964
4965 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4966 public:
4967 virtual bool doHeapRegion(HeapRegion* r) {
4968 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4969 G1CollectedHeap::heap()->clear_in_cset(r);
4970 r->set_young_index_in_cset(-1);
4971 return false;
4972 }
4973 };
4974
4975 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4976 G1AbandonCollectionSetClosure cl;
4977 collection_set->iterate(&cl);
4978
4979 collection_set->clear();
4980 collection_set->stop_incremental_building();
4981 }
4982
4983 void G1CollectedHeap::set_free_regions_coming() {
4984 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4985
4986 assert(!free_regions_coming(), "pre-condition");
4987 _free_regions_coming = true;
4988 }
4989
4990 void G1CollectedHeap::reset_free_regions_coming() {
4991 assert(free_regions_coming(), "pre-condition");
4992
4993 {
4994 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4995 _free_regions_coming = false;
4996 SecondaryFreeList_lock->notify_all();
4997 }
4998
4999 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5000 }
5001
5002 void G1CollectedHeap::wait_while_free_regions_coming() {
5003 // Most of the time we won't have to wait, so let's do a quick test
5004 // first before we take the lock.
5005 if (!free_regions_coming()) {
5006 return;
5007 }
5008
5009 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5010
5011 {
5012 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5013 while (free_regions_coming()) {
5014 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5015 }
5016 }
5017
5018 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5019 }
5020
5021 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5022 return _allocator->is_retained_old_region(hr);
5023 }
5024
5025 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5026 _eden.add(hr);
5027 _g1_policy->set_region_eden(hr);
5028 }
5029
5030 #ifdef ASSERT
5031
5032 class NoYoungRegionsClosure: public HeapRegionClosure {
5033 private:
5034 bool _success;
5035 public:
5036 NoYoungRegionsClosure() : _success(true) { }
5037 bool doHeapRegion(HeapRegion* r) {
5038 if (r->is_young()) {
5039 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5040 p2i(r->bottom()), p2i(r->end()));
5041 _success = false;
5042 }
5043 return false;
5044 }
5045 bool success() { return _success; }
5046 };
5047
5048 bool G1CollectedHeap::check_young_list_empty() {
5049 bool ret = (young_regions_count() == 0);
5050
5051 NoYoungRegionsClosure closure;
5052 heap_region_iterate(&closure);
5053 ret = ret && closure.success();
5054
5055 return ret;
5056 }
5057
5058 #endif // ASSERT
5059
5060 class TearDownRegionSetsClosure : public HeapRegionClosure {
5061 private:
5062 HeapRegionSet *_old_set;
5063
5064 public:
5065 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5066
5067 bool doHeapRegion(HeapRegion* r) {
5068 if (r->is_old()) {
5069 _old_set->remove(r);
5070 } else if(r->is_young()) {
5071 r->uninstall_surv_rate_group();
5072 } else {
5073 // We ignore free regions, we'll empty the free list afterwards.
5074 // We ignore humongous regions, we're not tearing down the
5075 // humongous regions set.
5076 assert(r->is_free() || r->is_humongous(),
5077 "it cannot be another type");
5078 }
5079 return false;
5080 }
5081
5082 ~TearDownRegionSetsClosure() {
5083 assert(_old_set->is_empty(), "post-condition");
5084 }
5085 };
5086
5087 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5088 assert_at_safepoint(true /* should_be_vm_thread */);
5089
5090 if (!free_list_only) {
5091 TearDownRegionSetsClosure cl(&_old_set);
5092 heap_region_iterate(&cl);
5093
5094 // Note that emptying the _young_list is postponed and instead done as
5095 // the first step when rebuilding the regions sets again. The reason for
5096 // this is that during a full GC string deduplication needs to know if
5097 // a collected region was young or old when the full GC was initiated.
5098 }
5099 _hrm.remove_all_free_regions();
5100 }
5101
5102 void G1CollectedHeap::increase_used(size_t bytes) {
5103 _summary_bytes_used += bytes;
5104 }
5105
5106 void G1CollectedHeap::decrease_used(size_t bytes) {
5107 assert(_summary_bytes_used >= bytes,
5108 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5109 _summary_bytes_used, bytes);
5110 _summary_bytes_used -= bytes;
5111 }
5112
5113 void G1CollectedHeap::set_used(size_t bytes) {
5114 _summary_bytes_used = bytes;
5115 }
5116
5117 class RebuildRegionSetsClosure : public HeapRegionClosure {
5118 private:
5119 bool _free_list_only;
5120 HeapRegionSet* _old_set;
5121 HeapRegionManager* _hrm;
5122 size_t _total_used;
5123
5124 public:
5125 RebuildRegionSetsClosure(bool free_list_only,
5126 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5127 _free_list_only(free_list_only),
5128 _old_set(old_set), _hrm(hrm), _total_used(0) {
5129 assert(_hrm->num_free_regions() == 0, "pre-condition");
5130 if (!free_list_only) {
5131 assert(_old_set->is_empty(), "pre-condition");
5132 }
5133 }
5134
5135 bool doHeapRegion(HeapRegion* r) {
5136 if (r->is_empty()) {
5137 // Add free regions to the free list
5138 r->set_free();
5139 r->set_allocation_context(AllocationContext::system());
5140 _hrm->insert_into_free_list(r);
5141 } else if (!_free_list_only) {
5142
5143 if (r->is_humongous()) {
5144 // We ignore humongous regions. We left the humongous set unchanged.
5145 } else {
5146 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5147 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
5148 r->move_to_old();
5149 _old_set->add(r);
5150 }
5151 _total_used += r->used();
5152 }
5153
5154 return false;
5155 }
5156
5157 size_t total_used() {
5158 return _total_used;
5159 }
5160 };
5161
5162 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5163 assert_at_safepoint(true /* should_be_vm_thread */);
5164
5165 if (!free_list_only) {
5166 _eden.clear();
5167 _survivor.clear();
5168 }
5169
5170 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5171 heap_region_iterate(&cl);
5172
5173 if (!free_list_only) {
5174 set_used(cl.total_used());
5175 if (_archive_allocator != NULL) {
5176 _archive_allocator->clear_used();
5177 }
5178 }
5179 assert(used_unlocked() == recalculate_used(),
5180 "inconsistent used_unlocked(), "
5181 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5182 used_unlocked(), recalculate_used());
5183 }
5184
5185 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5186 HeapRegion* hr = heap_region_containing(p);
5187 return hr->is_in(p);
5188 }
5189
5190 // Methods for the mutator alloc region
5191
5192 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5193 bool force) {
5194 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5195 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5196 if (force || should_allocate) {
5197 HeapRegion* new_alloc_region = new_region(word_size,
5198 false /* is_old */,
5199 false /* do_expand */);
5200 if (new_alloc_region != NULL) {
5201 set_region_short_lived_locked(new_alloc_region);
5202 _hr_printer.alloc(new_alloc_region, !should_allocate);
5203 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5204 return new_alloc_region;
5205 }
5206 }
5207 return NULL;
5208 }
5209
5210 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5211 size_t allocated_bytes) {
5212 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5213 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5214
5215 collection_set()->add_eden_region(alloc_region);
5216 increase_used(allocated_bytes);
5217 _hr_printer.retire(alloc_region);
5218 // We update the eden sizes here, when the region is retired,
5219 // instead of when it's allocated, since this is the point that its
5220 // used space has been recored in _summary_bytes_used.
5221 g1mm()->update_eden_size();
5222 }
5223
5224 // Methods for the GC alloc regions
5225
5226 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5227 if (dest.is_old()) {
5228 return true;
5229 } else {
5230 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5231 }
5232 }
5233
5234 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5235 assert(FreeList_lock->owned_by_self(), "pre-condition");
5236
5237 if (!has_more_regions(dest)) {
5238 return NULL;
5239 }
5240
5241 const bool is_survivor = dest.is_young();
5242
5243 HeapRegion* new_alloc_region = new_region(word_size,
5244 !is_survivor,
5245 true /* do_expand */);
5246 if (new_alloc_region != NULL) {
5247 // We really only need to do this for old regions given that we
5248 // should never scan survivors. But it doesn't hurt to do it
5249 // for survivors too.
5250 new_alloc_region->record_timestamp();
5251 if (is_survivor) {
5252 new_alloc_region->set_survivor();
5253 _survivor.add(new_alloc_region);
5254 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5255 } else {
5256 new_alloc_region->set_old();
5257 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5258 }
5259 _hr_printer.alloc(new_alloc_region);
5260 bool during_im = collector_state()->during_initial_mark_pause();
5261 new_alloc_region->note_start_of_copying(during_im);
5262 return new_alloc_region;
5263 }
5264 return NULL;
5265 }
5266
5267 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5268 size_t allocated_bytes,
5269 InCSetState dest) {
5270 bool during_im = collector_state()->during_initial_mark_pause();
5271 alloc_region->note_end_of_copying(during_im);
5272 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5273 if (dest.is_old()) {
5274 _old_set.add(alloc_region);
5275 }
5276 _hr_printer.retire(alloc_region);
5277 }
5278
5279 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5280 bool expanded = false;
5281 uint index = _hrm.find_highest_free(&expanded);
5282
5283 if (index != G1_NO_HRM_INDEX) {
5284 if (expanded) {
5285 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5286 HeapRegion::GrainWords * HeapWordSize);
5287 }
5288 _hrm.allocate_free_regions_starting_at(index, 1);
5289 return region_at(index);
5290 }
5291 return NULL;
5292 }
5293
5294 // Optimized nmethod scanning
5295
5296 class RegisterNMethodOopClosure: public OopClosure {
5297 G1CollectedHeap* _g1h;
5298 nmethod* _nm;
5299
5300 template <class T> void do_oop_work(T* p) {
5301 T heap_oop = oopDesc::load_heap_oop(p);
5302 if (!oopDesc::is_null(heap_oop)) {
5303 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5304 HeapRegion* hr = _g1h->heap_region_containing(obj);
5305 assert(!hr->is_continues_humongous(),
5306 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5307 " starting at " HR_FORMAT,
5308 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5309
5310 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5311 hr->add_strong_code_root_locked(_nm);
5312 }
5313 }
5314
5315 public:
5316 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5317 _g1h(g1h), _nm(nm) {}
5318
5319 void do_oop(oop* p) { do_oop_work(p); }
5320 void do_oop(narrowOop* p) { do_oop_work(p); }
5321 };
5322
5323 class UnregisterNMethodOopClosure: public OopClosure {
5324 G1CollectedHeap* _g1h;
5325 nmethod* _nm;
5326
5327 template <class T> void do_oop_work(T* p) {
5328 T heap_oop = oopDesc::load_heap_oop(p);
5329 if (!oopDesc::is_null(heap_oop)) {
5330 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5331 HeapRegion* hr = _g1h->heap_region_containing(obj);
5332 assert(!hr->is_continues_humongous(),
5333 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5334 " starting at " HR_FORMAT,
5335 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5336
5337 hr->remove_strong_code_root(_nm);
5338 }
5339 }
5340
5341 public:
5342 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5343 _g1h(g1h), _nm(nm) {}
5344
5345 void do_oop(oop* p) { do_oop_work(p); }
5346 void do_oop(narrowOop* p) { do_oop_work(p); }
5347 };
5348
5349 // Returns true if the reference points to an object that
5350 // can move in an incremental collection.
5351 bool G1CollectedHeap::is_scavengable(oop obj) {
5352 HeapRegion* hr = heap_region_containing(obj);
5353 return !hr->is_pinned();
5354 }
5355
5356 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5357 guarantee(nm != NULL, "sanity");
5358 RegisterNMethodOopClosure reg_cl(this, nm);
5359 nm->oops_do(®_cl);
5360 }
5361
5362 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5363 guarantee(nm != NULL, "sanity");
5364 UnregisterNMethodOopClosure reg_cl(this, nm);
5365 nm->oops_do(®_cl, true);
5366 }
5367
5368 void G1CollectedHeap::purge_code_root_memory() {
5369 double purge_start = os::elapsedTime();
5370 G1CodeRootSet::purge();
5371 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5372 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5373 }
5374
5375 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5376 G1CollectedHeap* _g1h;
5377
5378 public:
5379 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5380 _g1h(g1h) {}
5381
5382 void do_code_blob(CodeBlob* cb) {
5383 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5384 if (nm == NULL) {
5385 return;
5386 }
5387
5388 if (ScavengeRootsInCode) {
5389 _g1h->register_nmethod(nm);
5390 }
5391 }
5392 };
5393
5394 void G1CollectedHeap::rebuild_strong_code_roots() {
5395 RebuildStrongCodeRootClosure blob_cl(this);
5396 CodeCache::blobs_do(&blob_cl);
5397 }
5398
5399 GCServicabilitySupport* G1CollectedHeap::create_servicability_support() {
5400 return new G1GCServicabilitySupport();
5401 }